Optical communication network system, wavelength routing apparatus, communication node, optical path managing method for use in optical cross connect apparatus, and apparatus for that method

ABSTRACT

An optical communication network system and a wavelength-routing device and a communication node therefor are provided which can easily increase the optical paths between communication nodes, which are capable of expanding transmission capacity, and which excel in flexibility and expandability. An optical signal within a wavelength band (λB m ±Δλ m ) which has been transmitted from a predetermined communication node ( 200 - 1  through  200 - 4 ) is subjected to wavelength-band demultiplexing of the wavelength bands by wavelength-band demultiplexers ( 220 - 1  through  220 - 4 ) of a wavelength-routing device ( 210 ), and is then subjected to wavelength-routing by arrayed-waveguide gratings ( 241  through  244 ) according to the wavelength bands, and furthermore is multiplexed with optical signals of other wavelength bands by wavelength-band multiplexers ( 230 - 1  through  230 - 4 ), and after having been outputted, is transmitted to a communication node. In this manner, by varying the wavelength band (λB m ±Δλ m ) of the wavelength of the optical signal which is transmitted from the communication node, it becomes possible to establish a single optical path between the communication nodes for each wavelength band.

TECHNICAL FIELD

The present invention relates to an optical communication network systemwhich takes advantage of wavelength-routing and which establishescommunication between a plurality of communication nodes by routecontrol according to the wavelength of an optical signal, to awavelength-routing device thereof, and to a communication node.

Furthermore, the present invention relates to an optical path managementmethod and a device therefor which are useful when applied to such anoptical communication network system, and to a technique for managingthe optical path in an optical cross connect device which forms anoptical network using an optical wavelength division multiplexingtechnique, and in particular an optical cross connect device whichconsists of a combination of a plurality of small scale optical matrixswitches, and which establishes an optical path between any desiredcommunication nodes among a maximum of N (where N is an integer greaterthan or equal to 2) communication nodes which transmit and receivewavelength division multiplexed signals which are obtained by wavelengthdivision multiplexing optical signals of a maximum of m wavelengths(where m is an integer greater than or equal to 2).

BACKGROUND ART

In recent years, communication traffic is constantly increasing alongwith the spread of broadband service and the increase in the utilizationof information interchange by companies which take advantage of theinternet, and demand for increase of the capacity and the rate ofcommunication networks is unrelenting.

The wavelength division multiplexing (WDM) communication techniquegreatly increases the transmission capacity per one optical fiber, andhas realized great capacity increase between two locations. However,when relaying the optical signal at a communication node, it isnecessary to demultiplex the wavelength division multiplexed signals foreach wavelength, and to route the data packets in each optical signalindividually for each packet.

Nowadays, routing of data packets is performed electrically byconverting the optical signal to an electrical signal, but, along withincreases in the transmission rate and increases in capacity, therouting by electrical processing of a high volume signal will reach alimit in the near future.

As a means for solving this problem, wavelength path routing isproposed, in which the optical signals are not converted into electricalsignals, but are routed in the optical state (upon the optical layer).

FIG. 25 is an optical communication network system based upon wavelengthpath routing which has been implemented using an arrayed-waveguidegrating which is provided with a wavelength-routing function (forexample, refer to “32×32 full-mesh (1024 path) wavelength-routing WDMnetwork based upon uniform-loss cyclic-frequency arrayed-waveguidegrating”, IEE Electron. Lett., vol. 36, no., pp. 1294-1295, 2000, by K.Kato et al.).

The optical communication network shown in FIG. 25 shows the case inwhich the number of the communication nodes is four, and 100-1 through100-4 are communication nodes, 110 is a 4×4 arrayed-waveguide gratinghaving four input ports and four output ports, 120-1 through 120-4 areupstream optical transmission lines along which pass optical signalswhich have been transmitted towards the arrayed-waveguide grating 110from the communication nodes 100-1 through 100-4, and 130-1 through130-4 are downstream optical transmission lines along which pass opticalsignals which have been transmitted from the arrayed-waveguide grating110 towards the communication nodes 100-1 through 100-4.

The arrayed-waveguide grating 110 is an optical component which hasinput ports 140-1 through 140-4 and output ports 150-1 through 150-4,and the output ports 150-1 through 150-4 which output the opticalsignals which have been inputted to the input ports 140-1 through 140-4are determined uniquely according to the wavelengths of these opticalsignals.

The upstream optical transmission lines 120-1 through 120-4 arerespectively connected to the input ports 140-1 through 140-4 of thearrayed-waveguide grating 110, while the downstream transmission lines130-1 through 130-4 are respectively connected to the output ports 150-1through 150-4 of the arrayed-waveguide grating 110.

FIGS. 26 and 27 show how the input ports 140-1 through 140-4 and theoutput ports 150-1 through 150-4 of the 4×4 arrayed-waveguide grating110, which has the four input ports 140-1 through 140-4 and the fouroutput ports 150-1 through 150-4, are connected together according towavelength.

FIG. 26 shows the case of a 4×4 arrayed-waveguide grating 110 which isprovided with a cyclic-wavelength characteristic, and moreover FIG. 27shows the case of one which is not provided with a cyclic-wavelengthcharacteristic.

For example, in FIG. 26, when an optical signal of wavelength λ3 hasbeen inputted to the input port 140-1, this optical signal of wavelengthλ3 is outputted from the output port 150-3. Accordingly, when an opticalsignal of wavelength λ3 is transmitted from the communication node100-1, this optical signal of wavelength λ3 is inputted to the inputport 140-1 of the arrayed-waveguide grating 110 via the opticaltransmission line 120-1, and, due to wavelength-routing, this opticalsignal of wavelength λ3 is outputted from the output port 150-3 of thearrayed-waveguide grating 110. Subsequently, the optical signal ofwavelength λ3 arrives at the communication node 100-3 along the opticaltransmission line 130-3. In this manner, it is possible to performrouting upon the optical layer based upon the wavelength of the opticalsignals by utilizing the wavelength-routing function of thearrayed-waveguide grating 110, and to perform communication between thecommunication nodes 100-1 through 100-4, without converting the opticalsignals into electrical signals.

Furthermore, an optical communication network having a structure asshown in FIG. 28 is known as a network system which is capable ofanswering to increase of transmission capacity by providing an opticalpath of two or more wavelengths between two communication nodes (referto Japanese Unexamined Patent Application, First Publications Nos.2000-134649, 2002-165238, and 2002-262319).

The optical communication network shown in FIG. 28 shows the case inwhich the number of communication nodes is four. In FIG. 28, 1200-1through 1200-4 denote communication nodes, 1220-1 through 1220-4 denotewavelength-band demultiplexing devices, 1230-1 through 1230-4 denotewavelength-band multiplexing devices, and 1240 denotes an opticalswitch.

The communication nodes 1200-1 through 1200-4 wavelength divisionmultiplex and output a plurality of optical signals. The optical signalswhich are outputted are inputted to the respective wavelength-banddemultiplexing devices 1220-1 through 1220-4. These wavelength-banddemultiplexing devices are provided with the function of distributingthe wavelength division multiplexed signals which have been inputted toa plurality of output ports. At this time, the signals which areoutputted from the respective output ports are wavelength divisionmultiplexed for each combination of wavelengths which are determined inadvance, in other words for each wavelength-band. The routes of theoptical signals which are outputted from the wavelength-banddemultiplexing devices are changed over by the optical switch 1240, andthe outputs thereof are inputted to the wavelength-band multiplexingdevices 1230-1 through 1230-4. These wavelength-band multiplexingdevices, in a manner opposite to the wavelength-band demultiplexingdevices, are provided with the function of bundling together signalswhich have been wavelength division multiplexed for each wavelength-bandto a single output port. The signals which have been outputted from thewavelength-band multiplexing devices 1230-1 through 1230-4 are inputtedto the communication nodes 1200-1 through 1200-4, and are receivedthereby.

Since it is possible to provide an optical path in this type of opticalcommunication network between two communication nodes for eachwavelength-band, accordingly it is possible to provide a plurality ofoptical paths between the communication nodes up to the number ofwavelengths which are included within a wavelength-band.

It should be understood that, as shown in FIG. 29, there is also a knownmethod of forming the optical switch 1240 by combining a plurality ofsmall scale optical switches 1240-1 through 1240-3 (refer to JapaneseUnexamined Patent Application, First Publication No. 2001-8244).

Moreover, it should be understood that there is known an opticalcommunication network (refer to Japanese Unexamined Patent Application,First Publication No. 2002-300137) which utilizes the CWDM (Coarse WDM)standard having a grid of 20 nm interval in the wavelength-banddemultiplexing devices or the wavelength-band multiplexing devices, andwhich forms wavelength-bands in which DWDM (Dense WDM) signals of 100GHz (about 0.8 nm) intervals are accommodated in the 20 nm bands.

However, with the above-described conventional optical communicationnetwork system based upon wavelength-routing of the arrayed-waveguidegrating 110, although the communication node 100-1 can transmitinformation to the communication node 100-3 with an optical signal ofwavelength λ3, it is difficult to increase the transmission capacityfrom the communication node 100-1 to the communication node 100-3 abovethe transmission capacity of an optical signal of one wavelength.

In other words, it is only possible to establish a single optical pathbetween two communication nodes with the conventional technique shown inFIG. 25. In this manner, with an optical communication network system ofthe conventional structure which is based upon wavelength-routing by anarrayed-waveguide grating 110, there is the problematical aspect that itis extremely difficult to increase the transmission capacity byincreasing the number of optical paths between the communication nodes.

Furthermore, with the method of establishing an optical path betweencommunication nodes for each wavelength-band, the number ofcommunication nodes to which some communication node can transmitinformation is limited to the number of wavelength-bands, and there isthe problem that, if the number of communication nodes exceeds thenumber of the wavelength-bands, then a combination of the communicationnodes is created in which information is not delivered unless it istransmitted via other communication nodes.

On the other hand, FIG. 30 shows an example of a conventional opticalcross connect device (refer to “Optical Networks”, R. Ramaswami, K. N.Sivarajan, Morgan Kaufman Publishers Inc., 1998, p. 341 etc.). In thisfigure, 1-1, 1-2, . . . 1-N are wavelength division demultiplexingcircuits, 2-1, 2-2, . . . 2-N are wavelength division multiplexingcircuits, 3-1, 3-2, . . . 3-m are optical matrix switches, 4-1, 4-2, . .. 4-N are input optical fibers (optical transmission lines upon theinput side), and 5-1, 5-2, . . . 5-N are output optical fibers (opticaltransmission lines upon the output side).

The wavelength division demultiplexing circuits 1-1 through 1-N eachhave a single input port and m output ports, and the input port isconnected via the input optical fibers 4-1 through 4-N to a certainsingle communication node (not shown in the figure), and a wavelengthdivision multiplexed signal which has been inputted from the certaincommunication node to the input port is demultiplexed by wavelength andis outputted from the respective output ports.

The wavelength division multiplexing circuits 2-1 through 2-N each has minput ports and a single output port, and the output port is connectedto a certain communication node (not shown in the figure) via outputoptical fibers 5-1 through 5-N, so that optical signals of a maximum ofm wavelengths which have been inputted to the respective input ports arewavelength division multiplexed to form a wavelength divisionmultiplexed signal, which is outputted from the output port to thecertain communication node.

The optical matrix switches 3-1 through 3-m each has N input ports and Noutput ports, and each of the input ports is respectively connected tothat output port, among the output ports of the wavelength divisiondemultiplexing circuits 1-1 through 1-N, which outputs an optical signalof the same wavelength, while each of the output ports is separatelyconnected to the input ports of the wavelength division multiplexingcircuits 2-1 through 2-N.

With this type of optical cross connect device, the wavelength divisionmultiplexed signals of m wavelengths which have been transmitted via theinput optical fibers 4-1 through 4-N from the respective communicationnodes are inputted to the wavelength division demultiplexing circuits1-1 through 1-N, are demultiplexed by wavelength, are outputted from theseparate output ports, and are respectively inputted by wavelength tothe different optical matrix switches 3-1 through 3-m. Routes, that is,the wavelength division multiplexing circuits 2-1 through 2-N which arethe output destination, are changed over so that the optical signalswhich have been inputted to the optical matrix switches 3-1 through 3-mare outputted to the desired output optical fibers 5-1 through 5-N underthe condition that optical signals of the same wavelength are notoutputted from the same output optical fiber, in other words, under thecondition that optical signals of the same wavelength are not inputtedto the same wavelength division multiplexing circuit, and the opticalsignals of m wavelengths which have been inputted to the wavelengthdivision multiplexing circuits 2-1 through 2-N are wavelength divisionmultiplexed, and are transmitted to the respective communication nodesvia the output optical fibers 5-1 through 5-N.

With the circuit of FIG. 30, it is possible to establish settings sothat all the optical signals of all the wavelengths which have beenmultiplexed upon the input optical fibers are outputted from the desiredoutput optical fibers. However, due to the condition that opticalsignals of the same wavelength are not outputted from the same outputoptical fiber, the optical paths between the input optical fibers andthe output optical fibers cannot be set freely.

For example, the case may be considered in which the number of the inputoptical fibers and the number of the output optical fibers are both 8,and the number of multiplexed wavelengths is 4. At this time, under theconditions that the optical paths between the input optical fibers andthe output optical fibers are not arranged, that is, as shown in FIGS.31A through 31D, optical paths which use the wavelength λ1 areestablished between the #1 input optical fiber and the #3 output opticalfiber and between the #3 input optical fiber and the #1 output opticalfiber, optical paths which use the wavelength λ2 are established betweenthe #2 input optical fiber and the #5 output optical fiber and betweenthe #5 input optical fiber and the #2 output optical fiber, opticalpaths which use the wavelength λ3 are established between the #2 inputoptical fiber and the #8 output optical fiber and between the #8 inputoptical fiber and the #2 output optical fiber; and optical paths whichuse the wavelength λ4 are established between the #1 input optical fiberand the #3 output optical fiber and between the #3 input optical fiberand the #1 output optical fiber, it is not possible to implement settingof the optical matrix switches so as to establish an optical pathbetween the #1 input optical fiber and the #2 output optical fiber, orbetween the #2 input optical fiber and the #1 output optical fiber, evenusing the optical matrix switches through which any of the wavelengthsfrom λ1 through λ4 passes, since a signal of the same wavelength as analready existing optical path is being outputted from the same outputoptical fiber.

On the other hand, as another method for implementing the establishmentof optical paths between the input optical fibers and output opticalfibers, there is a method as shown in FIGS. 32A through 32D, in whichthe optical paths between the input optical fibers and the outputoptical fibers are arranged. In detail, there is the method in which:optical paths which use the wavelength λ1 are established between the #1input optical fiber and the #3 output optical fiber and between the #3input optical fiber and the #1 output optical fiber; optical paths whichuse the wavelength λ1 are established between the #2 input optical fiberand the #5 output optical fiber and between the #5 input optical fiberand the #2 output optical fiber; optical paths which use the wavelengthλ2 are established between the #2 input optical fiber and the #8 outputoptical fiber and between the #8 input optical fiber and the #2 outputoptical fiber; and optical paths which use the wavelength λ2 areestablished between the #1 input optical fiber and the #3 output opticalfiber and between the #3 input optical fiber and the #1 output opticalfiber.

In these circumstances, it is possible to utilize the wavelength λ3 orthe wavelength λ4 for setting of the optical matrix switches so as toestablish a further optical path between the #1 optical fiber and the #2optical fiber, and, as compared with the previous case, it is possibleto enhance the efficiency of utilization of the optical matrix switches.

In this manner, in order to utilize an optical cross connect deviceformed by combining small scale optical matrix switches efficiently, itis necessary to establish an optical path by planning a method ofutilizing wavelengths so as to enhance efficiency.

DISCLOSURE OF INVENTION

The present invention has been conceived in the light of theabove-described problems, and its object is to provide an opticalcommunication network system and a wavelength-routing device and acommunication node therefor, which can easily increase the number ofoptical paths between the communication nodes and are capable ofincreasing the transmission capacity, and which excel in flexibility andexpandability.

Furthermore, an object of the present invention is to provide an opticalcommunication network system and a wavelength-routing device and acommunication node therefor which provide full mesh connectivity inwhich optical paths are established between all the communication nodesby utilizing an arrayed-waveguide grating for wavelength-routing.

Yet furthermore, an object of the present invention is to provide anoptical path management method and a device therefor, which can increasethe efficiency of utilization of an optical cross connect device whichis formed by combining small scale optical matrix switches.

In order to attain the above-described objects, the present invention isan optical communication network system comprising: a plurality ofcommunication nodes; a wavelength-routing device which establishescommunication between the communication nodes based upon route controlaccording to the wavelength of an optical signal; and an opticaltransmission line which forms a communication path which connects thecommunication nodes and the wavelength-routing device, wherein thewavelength-routing device comprises: N device input ports, where N beingan integer greater than or equal to 2, which are connected via theoptical transmission line to the communication nodes; N device outputports which are connected via the optical transmission line to thecommunication nodes; a plurality of wavelength-band demultiplexers whichare provided to each of the N device input ports, and each has a singleinput port and a plurality of output ports, and the input port isconnected to one of the device input ports; a plurality ofwavelength-band multiplexers which are provided to each of the N deviceoutput ports, and each has a plurality of input ports and a singleoutput port, and the output port is connected to one of the deviceoutput ports; and R K×K arrayed-waveguide gratings, where R being aninteger greater than or equal to J and J being an integer greater thanor equal to 2, which have K input ports and K output ports, where Kbeing an integer that satisfies K=N, which have wavelength-routingcharacteristics in which optical signals having different wavelengthswhich are inputted to one input port are output at different outputports depending on the wavelengths of the inputted optical signals andin which optical signals having different wavelengths which areoutputted from one output port are optical signals which have beeninputted to different input ports, and wherein the wavelength-banddemultiplexers comprise a means which demultiplexes by wavelength band awavelength division multiplexed signal in which a respectivepredetermined number of wavelengths have been wavelength divisionmultiplexed for each wavelength band which is transmitted from thecommunication nodes, where wavelength band=central wavelengthλB_(m)±wavelength band width Δλ_(m), withλB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), where 1=m=R−1, with m being an integer,and outputs the results at different output ports, the wavelength-bandmultiplexers comprise a means which multiplexes optical signals whichhave been inputted from the plurality of input ports for each wavelengthband and which outputs a wavelength division multiplexed signal in whicha predetermined number of wavelengths have been wavelength divisionmultiplexed at the output port, the K×K arrayed-waveguide gratings areprovided with a wavelength-routing characteristic for each wavelengthband of central wavelength λB₁±wavelength band width Δλ₁, centralwavelength λB₂±wavelength band width Δλ₂ (λB₁+Δλ₁<λB₂−Δλ₂), centralwavelength λB₃±wavelength band width Δλ₃ (λB₂+Δλ₂<λB₃−Δλ₃), . . . ,central wavelength λB_(R)±wavelength band width Δλ_(R)(λB_(R−1)+Δλ_(R−1)<λB_(R)−Δλ_(R)), the output ports of thewavelength-band demultiplexers which are respectively connected to the Ndevice input ports are one to one connected to the input ports of theK×K arrayed-waveguide gratings which have wavelength-routingcharacteristics at the wavelength bands of the optical signals which areoutputted from the output ports of the wavelength-band demultiplexers,and the output ports of the K×K arrayed-waveguide gratings are one toone connected to the input ports of any one of the plurality ofwavelength-band multiplexers which can multiplex optical signals ofwavelengths which belong to the wavelength bands of the optical signalswhich are outputted from the output ports of the K×K arrayed-waveguidegratings.

According to the present invention, when, for example, an optical signalwithin the λB_(m)±Δλ_(m) wavelength band is outputted from apredetermined communication node, this optical signal is transmittedalong the optical transmission line and arrives at an input port of thewavelength-band demultiplexer of the wavelength-routing device,wavelength-band demultiplexing of the wavelength bands is performed bythe wavelength-band demultiplexer, and the results are outputted from apredetermined output port. The optical signal which is outputted fromthe output port of the wavelength-band demultiplexer is inputted to aninput port of the arrayed-waveguide grating according to its wavelengthband.

From the relationship between the input ports/output ports of thearrayed-waveguide grating and wavelengths, the optical signal which hasbeen inputted to the input port of the arrayed-waveguide grating isoutputted at a predetermined output port of the arrayed-waveguidegrating.

An optical signal which has been outputted from the output port of thearrayed-waveguide grating is inputted to an input port of thewavelength-band multiplexer, and is multiplexed by the wavelength-bandmultiplexer with optical signals of other wavelength bands, then beingoutputted from an output port.

The optical signal which has been outputted from the output port of thewavelength-band multiplexer is transmitted along the opticaltransmission line, and arrives at a communication node.

By doing this, when transmitting data from one communication node toanother communication node, it is possible to utilize the optical pathsfor each wavelength band by varying the wavelength band λB_(m)±Δλ_(m) ofthe wavelength of the optical signal which is transmitted from thecommunication node.

The communication nodes and the wavelength-routing device which make upthe optical communication network system are connected by pairs ofoptical fibers in the same manner as in the conventional example, but,with the present invention, an arrayed-waveguide grating is arrangedindependently for each wavelength band in the wavelength-routing device,and by performing wavelength-band multiplexing of wavelength bands andwavelength-band demultiplexing of wavelength bands in each communicationnode and the wavelength-routing device, it is possible to form oneoptical path for each wavelength band between the communication nodes.

Accordingly, although with the conventional technique shown in FIG. 25it is possible to form only a single optical path between thecommunication nodes with a pair of optical transmission lines, byapplying the structure of the present invention, it is possible to form,at a maximum, the same number of optical paths as the number ofwavelength bands, and it is possible easily to increase the transmissioncapacity between the communication nodes.

Furthermore, with the optical communication network system of thepresent invention, when increasing the number of optical paths, it willbe sufficient to add the required equipment only between thecommunication nodes for which this increase of the number of opticalpaths is required, so that the flexibility and the economy are superb.

Yet further, with a conventional optical communication system in whichthe optical paths are formed between the communication nodes by takingthe wavelength-bands as units, when the number of communication nodesexceeds the number of the wavelength-bands, it is necessary to pass viaa different communication node. In contrast, according to the presentinvention, it is possible to implement an optical communication networksystem which provides full mesh connectivity in which optical paths areprovided between all the communication nodes. Accordingly, even if thenumber of communication nodes exceeds the number of thewavelength-bands, it is not necessary to pass via a differentcommunication node.

Furthermore, in the optical communication network system of theabove-described structure, each of the communication nodes may comprise:a J×1 wavelength-band multiplexer, where J being an integer greater thanor equal to 2, which has J input ports IP [1], IP [2], IP [3], . . . IP[J] and a single output port, and outputs at the single output portoptical signals of wavelengths which belong to the wavelength bands ofcentral wavelength λB₁±wavelength band width Δλ₁, central wavelengthλB₂±wavelength band width Δλ₂, central wavelength λB₃±wavelength bandwidth Δλ₃, . . . , central wavelength λB_(J)±wavelength band widthΔλ_(J), which are inputted to the respective J input ports, whereλB_(m)+Δλ_(m)=λB_(m+1)−αΔλ_(m+1), for 1=m=J−1, where m being an integer;a plurality of wavelength division multiplexers which are provided ateach of the input ports IP [1], IP [2], IP [3], . . . IP [J] of the J×1wavelength-band multiplexer, and which have two or more input ports andone output port, with the output ports being connected to the inputports of the J×1 wavelength-band multiplexer; and a plurality of opticaltransmitters which are connected to the input ports of the wavelengthdivision multiplexers, and which emit light of wavelengths which belongto wavelength bands of central wavelengths, λB_(m)±wavelength band widthΔλm, and wherein the output port of the J×1 wavelength-band multiplexermay be connected via an optical waveguide to the device input ports ofthe wavelength-routing device.

According to this structure, a communication node can transmit opticalsignals of different wavelengths within a different plurality ofcommunication wavelength bands. Accordingly, whereas the conventionaltechnique shown in FIG. 25 can form only a single optical path betweenthe communication nodes with a pair of optical transmission lines, byapplying the structure of the present invention, it is possible to form,as a maximum, the same number of optical paths as the number ofwavelength bands, so that it is possible easily to increase thetransmission capacity between the communication nodes. Furthermore, withthe optical communication network system of the present invention, whenincreasing the number of optical paths, it will be sufficient to add therequired equipment only between the communication nodes for which thisincrease of the number of optical paths is required, so that theflexibility and the economy are superb.

Furthermore, in an optical communication network system of theabove-described structure, each of the communication nodes may comprise:a 1×J wavelength-band demultiplexer, where J being an integer greaterthan or equal to 2, which has J output ports OP[1], OP[2], OP[3], . . .OP[J] and a single input port, and which outputs at the J output portsoptical signals of wavelengths which belong to the wavelength bandwidths which are inputted to the single input port of central wavelengthλB₁±wavelength band width Δλ₁, central wavelength λB₂±wavelength bandwidth Δλ₂, central wavelength λB₃±wavelength band width Δλ₃, . . . ,central wavelength λB_(J)±wavelength band width Δλ_(J), whereλB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), where m being an integer; a pluralityof wavelength division demultiplexers which are provided to each of theoutput ports OP[1], OP[2], OP[3], . . . OP[J] of the 1×J wavelength-banddemultiplexer, each of which has two or more output ports and a singleinput port, and the input port is connected to one of the output portsof the 1×J wavelength-band demultiplexer; and a plurality of opticalreceivers which are connected to the output ports of the wavelengthdivision demultiplexers, and wherein the single input port of the 1×Jwavelength-band demultiplexer may be connected via an optical waveguideto one of the device output ports of the wavelength-routing device.

According to this structure, a communication node can receive opticalsignals of different wavelengths within a different plurality ofcommunication wavelength bands. Accordingly, whereas the conventionaltechnique shown in FIG. 25 can form only a single optical path betweenthe communication nodes with a pair of optical transmission lines, byapplying the structure of the present invention, it is possible to form,as a maximum, the same number of optical paths as the number ofwavelength bands, so that it is possible easily to increase thetransmission capacity between the communication nodes. Furthermore, withthe optical communication network system of the present invention, whenincreasing the number of optical paths, it will be sufficient to add therequired equipment only between the communication nodes for which thisincrease of the number of optical paths is required, so that theflexibility and the economy are superb.

Furthermore, in an optical communication network system of theabove-described structure, each of the communication nodes may comprise:a J×1 wavelength-band multiplexer, where J being an integer greater thanor equal to 2, which has J input ports IP [1], IP [2], IP [3], . . . IP[J] and a single output port, and outputs at the single output portoptical signals of wavelengths which belong to the wavelength bands ofcentral wavelength λB₁±wavelength band width Δλ₁, central wavelengthλB₂±wavelength band width Δλ₂, central wavelength λB₃±wavelength bandwidth αλ₃, . . . , central wavelength λB_(J)±wavelength band widthΔλ_(J), which are inputted to each of the J input ports, whereλB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), for 1=m=J−1, where m being an integer;at least one wavelength-tunable optical light source integrated opticaltransmitter which is connected to any one of the input ports IP [1], IP[2], IP [3], . . . IP [J] of the J×1 wavelength-band multiplexer, whichis provided with a wavelength-tunable optical light source which can beset to a wavelength within a wavelength band which belongs to the inputport which is connected, and which outputs light of the wavelength; aplurality of wavelength division multiplexers which are provided to eachof the input ports of the J×1 wavelength-band multiplexer, other thanthe input port to which the wavelength-tunable optical light sourceintegrated optical transmitter is connected, and which have two or moreinput ports and one output port, with the output port being connected toone of the input ports of the J×1 wavelength-band multiplexer; aplurality of optical transmitters which are connected to the input portsof the wavelength division multiplexer, and which emit light ofwavelength which belongs to a wavelength band of central wavelengthλB_(m)±wavelength band width Δλm; a 1×J wavelength-band demultiplexer,where J being an integer greater than or equal to 2, which has J outputports OP[1], OP[2], OP[3], . . . OP[J] and a single input port, andoutputs at the J output ports optical signals of wavelengths whichbelong to the wavelength band widths of central wavelengthλB₁±wavelength band width Δλ₁, central wavelength λB₂±wavelength bandwidth Δλ₂, central wavelength λB₃±wavelength band width αλ₃, . . . ,central wavelength λB_(J)±wavelength band width Δλ_(J), which areinputted to the single input port, whereλB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), for 1=m=J, where m being an integer; anoptical receiver which is connected to that output port, among theoutput ports OP[1], OP[2], OP[3], . . . OP[J] of the 1×J wavelength-banddemultiplexer, which belongs to the wavelength band to which thewavelength-tunable optical light source integrated optical transmitteris provided, and which receives an optical signal of the wavelengthwhich is outputted from the wavelength-tunable optical light sourceintegrated optical transmitter; a plurality of wavelength divisiondemultiplexers which are provided to each of the output ports of the 1×Jwavelength-band demultiplexer, except for the output port to which theoptical receiver is connected, which have two or more, output ports anda single input port, and the input port is connected to one of theoutput ports of the 1×J wavelength-band demultiplexer; and a pluralityof optical receivers which are connected to the output ports of thewavelength division demultiplexers, and wherein the single input port ofthe 1×J wavelength-band demultiplexer is connected via an opticalwaveguide to one of the device output ports of the wavelength-routingdevice.

According to this structure, an optical signal is inputted at any one ofthe input ports IP [1], IP [2], IP [3], . . . IP [J] of the J×1wavelength-band multiplexer from at least one wavelength-tunable opticallight source integrated optical transmitter which is provided with thewavelength-tunable optical light source which can be set to a wavelengthwithin the wavelength band which belongs to the input port withoutpassing through the wavelength division multiplexer, and, among theoutput ports OP[1], OP[2], OP[3], . . . OP[J] of the 1×J wavelength-banddemultiplexer, an optical signal which has been outputted from an outputport which belongs to a wavelength band which is provided to thewavelength-tunable optical light source integrated optical transmitter,in other words an optical signal of the wavelength which has beenoutputted from the wavelength-tunable optical light source integratedoptical transmitter, is inputted to an optical receiver without passingthrough the optical division demultiplexer.

Furthermore, the optical communication network system of theabove-described structure may further comprise an optical pathmanagement means which controls an optical path between two differentcommunication nodes, and wherein if at least one group of thewavelength-tunable optical light source integrated optical transmittersexists which are provided to all the communication nodes and whichoutput optical signals of the same wavelength band, and if there are Kwavelength bands, where K being an integer greater than or equal to 2,which belong to the input ports of the J×1 wavelength-band multiplexerwhich are connected to the wavelength-tunable optical light sourceintegrated optical transmitters, the optical path management means mayassign mutually different priority rankings from 1 to K to thewavelength bands which belong to the input ports of the J×1wavelength-band multiplexer which are connected to thewavelength-tunable optical light source integrated optical transmitters,and when, among the wavelength bands which belong to the input ports ofthe J×1 wavelength-band multiplexer which are connected to thewavelength-tunable optical light source integrated optical transmitters,the highest numbered priority ranking among the wavelength bands forwhich optical paths exist between x-th communication node and y-thcommunication node is number b, and the lowest numbered priority rankingamong the wavelength bands for which an optical path whose start pointis the x-th communication node, an optical path whose end point is thex-th communication node, an optical path whose start point is the y-thcommunication node, and an optical path whose end point is the y-thcommunication node do not exist is number a, and the number a is smallerthan the number b, the optical path management means may establish anoptical path between the x-th communication node and the y-thcommunication node upon the wavelength band of a-th priority ranking,and thereafter controls ON/OFF and an oscillation wavelength of thewavelength-tunable optical light source integrated optical transmitterso as to cancel the optical path which was established between the x-thcommunication node and the y-th communication node upon the wavelengthband of b-th priority ranking.

Furthermore, in the above-described optical network communicationsystem, there may be further comprised: a database which records anoptical path for each wavelength band; a first search means which, whena requirement has arisen newly to establish an optical path betweenxx-th communication node and yy-th communication node, searches in thedatabase, in order from data which correspond to a wavelength band whosepriority ranking is the lowest, for a wavelength band which is not inuse by the xx-th communication node and the yy-th communication node; afirst transmission means which transmits to the optical path managementmeans a command for establishing an optical path according to the resultof searching by the first search means; a first database update meanswhich registers an optical path which has been newly established in thedatabase; a second search means which, when a requirement for an opticalpath which is already established between xxx-th communication node andyyy-th communication node has ceased, searches in the database, in orderfrom data which correspond to a wavelength band whose priority rankingis the highest, for a wavelength band upon which an optical path isestablished between the xxx-th communication node and the yyy-thcommunication node; a second transmission means which transmits to theoptical path management means a command for canceling an optical pathaccording to the result of searching by the second search means; asecond database update means which deletes an optical path which hasbeen cancelled from the database; an extraction means which searches inthe database the number b of the highest priority ranking among thewavelength bands upon which optical paths are established between thex-th communication node and the y-th communication node, and the numbera of the lowest priority ranking among the wavelength bands which do notuse both the x-th communication node and the y-th communication node,for all the combinations of x and y in a predetermined order, andextracts combinations of x, y, a, and b for which the number a issmaller than the number b; a third transmission means which, when anapplicable combination exists, transmits to the optical path managementmeans a command for establishing an optical path using the a-thwavelength band between the x-th communication node and the y-thcommunication node, and thereafter transmits to the optical pathmanagement means a command for canceling an optical path using the b-thwavelength band between the x-th communication node and the y-thcommunication node; and a database update means which registers anoptical path which has been newly established in the database, anddeletes an optical path which has been cancelled from the database.

By employing this type of structure, the state is brought about in whichthe optical paths between the communication nodes are always arranged,so that it is possible to enhance the efficiency of use of the opticalcross connect device.

Yet further, in the optical communication network system of theabove-described structure, the K×K arrayed-waveguide gratings may havecyclic-wavelength characteristics.

Even further, the present invention is a wavelength-routing device whichis provided to an optical communication network system comprising aplurality of communication nodes and an optical transmission line whichforms a communication path, connected with the communication nodes bythe optical transmission line, and which establishes communicationbetween the communication nodes based upon route control according tothe wavelength of an optical signal, the wavelength-routing devicecomprising: N device input ports, where N being an integer greater thanor equal to 2, which are connected via the optical transmission line tothe communication nodes; N device output ports which are connected viathe optical transmission line to the communication nodes; a plurality ofwavelength-band demultiplexers which are provided to each of the Ndevice input ports, and each has a single input port and a plurality ofoutput ports, and the input port is connected to one of the device inputports; a plurality of wavelength-band multiplexers which are provided toeach of the N device output ports, and each has a plurality of inputports and a single output port, and the output port is connected to oneof the device output ports; and R K×K arrayed-waveguide gratings, whereR being an integer greater than or equal to J and J being an integergreater than or equal to 2, which have K input ports and K output ports,where K being an integer that satisfies K=N, which havewavelength-routing characteristics in which optical signals havingdifferent wavelengths which are inputted to one input port are output atdifferent output ports depending on the wavelengths of the inputtedoptical signals and in which optical signals having differentwavelengths which are outputted from one output port are optical signalswhich have been inputted to different input ports, and wherein thewavelength-band demultiplexers comprise a means which demultiplexes bywavelength band a wavelength division multiplexed signal in which apredetermined number of wavelengths have been wavelength divisionmultiplexed for each wavelength band which is transmitted from thecommunication nodes, where wavelength band=central wavelengthλB_(m)±wavelength band width Δλ_(m), withλB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), where 1=m=R−1, with m being an integer,and outputs the results at different output ports, the wavelength-bandmultiplexers comprise a means which multiplexes optical signals whichhave been inputted from the plurality of input ports for each wavelengthband and which outputs a wavelength division multiplexed signal in whicha predetermined number of wavelengths have been wavelength divisionmultiplexed at the output port, the K×K arrayed-waveguide gratings areprovided with a wavelength-routing characteristic for each wavelengthband of central wavelength λB₁±wavelength band width Δλ₁, centralwavelength λB₂±wavelength band width Δλ₂ (λB₁+Δλ₁<λB₂−Δλ₂), centralwavelength λB₃±wavelength band width Δλ₃ (λB₂+Δλ₂<λB₃−Δλ₃), . . . ,central wavelength λB_(R)±wavelength band width Δλ_(R)(λB_(R−1)+Δλ_(R−1)<λB_(R)−Δλ_(R)), the output ports of thewavelength-band demultiplexers which are respectively connected to the Ndevice input ports are one to one connected to the input ports of theK×K arrayed-waveguide gratings which have wavelength-routingcharacteristics at the wavelength bands of the optical signals which areoutputted from the output ports of the wavelength-band demultiplexers,and the output ports of the K×K arrayed-waveguide gratings are one toone connected to the input ports of any one of the plurality ofwavelength-band multiplexers which can multiplex optical signals ofwavelengths which belong to the wavelength bands of the optical signalswhich are outputted from the output ports of the K×K arrayed-waveguidegratings.

Furthermore, the present invention is an optical path management devicewhich controls an optical path between two different communication nodesin an optical communication network system which comprises a pluralityof communication nodes, a wavelength-routing device which establishescommunication between the communication nodes based upon route controlaccording to the wavelength of an optical signal, and an opticaltransmission line which forms a communication path which connects thecommunication nodes and the wavelength-routing device wherein thewavelength-routing device comprises: N device input ports, where N beingan integer greater than or equal to 2, which are connected via theoptical transmission line to the communication nodes; N device outputports which are connected via the optical transmission line to thecommunication nodes; a plurality of wavelength-band demultiplexers whichare provided to each of the N device input ports, and each has a singleinput port and a plurality of output ports, and the input port isconnected to one of the device input ports; a plurality ofwavelength-band multiplexers which are provided to each of the N deviceoutput ports, and each has a plurality of input ports and a singleoutput port, and the output port is connected to one of the deviceoutput ports; and R K×K arrayed-waveguide gratings, where R being aninteger greater than or equal to J and J being an integer greater thanor equal to 2, which have K input ports and K output ports, where Kbeing an integer that satisfies K=N, which have wavelength-routingcharacteristics in which optical signals having different wavelengthswhich are inputted to one input port are output at different outputports depending on the wavelengths of the inputted optical signals andin which optical signals having different wavelengths which areoutputted from one output port are optical signals which have beeninputted to different input ports, and wherein the wavelength-banddemultiplexers comprise a means which demultiplexes by wavelength band awavelength division multiplexed signal in which a predetermined numberof wavelengths have been wavelength division multiplexed for eachwavelength band which is transmitted from the communication nodes,wherein wavelength band=central wavelength λB_(m)±wavelength band widthΔλ_(m), with λB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), where 1=m=R−1, with mbeing an integer, and outputs the results at different output ports, thewavelength-band multiplexers comprise a means which multiplexes opticalsignals which have been inputted from the plurality of input ports foreach wavelength band and which outputs a wavelength division multiplexedsignal in which a predetermined number of wavelengths have beenwavelength division multiplexed at the output port, the K×Karrayed-waveguide gratings are provided with a wavelength-routingcharacteristic for each wavelength band of central wavelengthλB₁±wavelength band width Δλ₁, central wavelength λB₂±wavelength bandwidth Δλ₂ (λB₁+Δλ₁<λB₂−Δλ₂), central wavelength λB₃±wavelength bandwidth Δλ₃ (λB₂+Δλ₂<λB₃−Δλ₃), . . . , central wavelength λB₃±wavelengthband width Δλ_(R) (λB_(R−1)+Δλ_(R−1)<λB_(R)−Δλ_(R)), the output ports ofthe wavelength-band demultiplexers which are respectively connected tothe N device input ports are one to one connected to the input ports ofthe K×K arrayed-waveguide gratings which have wavelength-routingcharacteristics at the wavelength bands of the optical signals which areoutputted from the output ports of the wavelength-band demultiplexers,and the output ports of the K×K arrayed-waveguide gratings are one toone connected to the input ports of any one of the plurality ofwavelength-band multiplexers which can multiplex optical signals ofwavelengths which belong to the wavelength bands of the optical signalswhich are outputted from the output ports of the K×K arrayed-waveguidegratings, and each of the communication nodes comprises: a J×1wavelength-band multiplexer, where J being an integer greater than orequal to 2, which has J input ports IP [1], IP [2], IP [3], . . . IP [J]and a single output port, and outputs at the single output port opticalsignals of wavelengths which belong to the wavelength bands of centralwavelength λB₁±wavelength band width Δλ₁, central wavelengthλB₂±wavelength band width Δλ₂, central wavelength λB₃±wavelength bandwidth Δλ₃, . . . , central wavelength λB_(J)±wavelength band widthΔλ_(J), which are inputted to each of the J input ports, whereλB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), for 1=m=J−1, where m being an integer;at least one wavelength-tunable optical light source integrated opticaltransmitter which is connected to any one of the input ports IP [1], IP[2], IP [3], . . . IP [J] of the J×1 wavelength-band multiplexer, whichis provided with a wavelength-tunable optical light source which can beset to a wavelength within a wavelength band which belongs to the inputport which is connected, and which outputs light of the wavelength; aplurality of wavelength division multiplexers which are provided to eachof the input ports of the J×1 wavelength-band multiplexer, other thanthe input port to which the wavelength-tunable optical light sourceintegrated optical transmitter is connected, and which have two or moreinput ports and one output port, with the output port being connected toone of the input ports of the J×1 wavelength-band multiplexer; aplurality of optical transmitters which are connected to the input portsof the wavelength division multiplexer; and which emit light ofwavelength which belongs to a wavelength band of central wavelengthλB_(m)±wavelength band width Δλm; a 1×J wavelength-band demultiplexer,where J being an integer greater than or equal to 2, which has J outputports OP[1], OP[2], OP[3], . . . OP[J] and a single input port, andoutputs at the J output ports optical signals of wavelengths whichbelong to the wavelength band widths of central wavelengthλB₁±wavelength band width Δλ₁, central wavelength λB₂±wavelength bandwidth Δλ₂, central wavelength λB₃±wavelength band width Δλ₃, . . . ,central wavelength λB_(J)±wavelength band width Δλ_(J), which areinputted to the single input port, whereλB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), for 1=m=J, where m being an integer; anoptical receiver which is connected to that output port, among theoutput ports OP[1], OP[2], OP[3], . . . OP[J] of the 1×J wavelength-banddemultiplexer, which belongs to the wavelength band to which thewavelength-tunable optical light source integrated optical transmitteris provided, and which receives an optical signal of the wavelengthwhich is outputted from the wavelength-tunable optical light sourceintegrated optical transmitter; a plurality of wavelength divisiondemultiplexers which are provided to each of the output ports of the 1×Jwavelength-band demultiplexer, except for the output port to which theoptical receiver is connected, which have two or more output ports and asingle input port, and the input port is connected to one of the outputports of the 1×J wavelength-band demultiplexer; and a plurality ofoptical receivers which are connected to the output ports of thewavelength division demultiplexers; and wherein the single input port ofthe 1×J wavelength-band demultiplexer is connected via an opticalwaveguide to one of the device output ports of the wavelength-routingdevice, and wherein the optical path management device comprises: ameans which, if at least one group of the wavelength-tunable opticallight source integrated optical transmitters exists which are providedto all the communication nodes and which output optical signals of thesame wavelength band, and if there are K wavelength bands, where K beingan integer greater than or equal to 2, which belong to the input portsof the J×1 wavelength-band multiplexer which are connected to thewavelength-tunable optical light source integrated optical transmitters,assigns mutually different priority rankings from 1 to K to thewavelength bands which belong to the input ports of the J×1wavelength-band multiplexer which are connected to thewavelength-tunable optical light source integrated optical transmitters;a means which detects that, among the wavelength bands which belong tothe input ports of the J×1 wavelength-band multiplexer which areconnected to the wavelength-tunable optical light source integratedoptical transmitters, the highest numbered priority ranking among thewavelength bands of optical paths between x-th communication node andy-th communication node is number b, and the lowest numbered priorityranking among the wavelength bands which are not used for an opticalpath whose start point is the x-th communication node, an optical pathwhose end point is the x-th communication node, an optical path whosestart point is the y-th communication node, and an optical path whoseend point is the y-th communication node is number a, and the number ais smaller than the number b; and a means which, if it has been detectedthat the number a is smaller than the number b, establishes an opticalpath between the x-th communication node and the y-th communication nodeupon the wavelength band of a-th priority ranking, and thereaftercontrols ON/OFF and an oscillation wavelength of the wavelength-tunableoptical light source integrated optical transmitter so as to cancel theoptical path which was established between the x-th communication nodeand the y-th communication node upon the wavelength band of b-thpriority ranking.

Furthermore, the present invention is an optical path management methodwhich controls an optical path between two different communication nodesin an optical communication network system which comprises a pluralityof communication nodes, a wavelength-routing device which establishescommunication between the communication nodes based upon route controlaccording to the wavelength of an optical signal, and an opticaltransmission line which forms a communication path which connects thecommunication nodes and the wavelength-routing device, wherein thewavelength-routing device comprises: N device input ports, where N beingan integer greater than or equal to 2, which are connected via theoptical transmission line to the communication nodes; N device outputports which are connected via the optical transmission line to thecommunication nodes; a plurality of wavelength-band demultiplexers whichare provided to each of the N device input ports, and each has a singleinput port and a plurality of output ports, and the input port isconnected to one of the device input ports; a plurality ofwavelength-band multiplexers which are provided to each of the N deviceoutput ports, and each has a plurality of input ports and a singleoutput port, and the output port is connected to one of the deviceoutput ports; and R K×K arrayed-waveguide gratings, where R being aninteger greater than or equal to J and J being an integer greater thanor equal to 2, which have K input ports and K output ports, where Kbeing an integer that satisfies K=N, which have wavelength-routingcharacteristics in which optical signals having different wavelengthswhich are inputted to one input port are output at different outputports depending on the wavelengths of the inputted optical signals andin which optical signals having different wavelengths which areoutputted from one output port are optical signals which have beeninputted to different input ports, wherein the wavelength-banddemultiplexers comprise a means which demultiplexes by wavelength band awavelength division multiplexed optical signal in which a predeterminednumber of wavelengths have been wavelength division multiplexed for eachwavelength band which is transmitted from the communication nodes, wherewavelength band=central wavelength λB_(m)±wavelength band width Δλ_(m),with λB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), where 1=m=R−1, with m being aninteger, and outputs the results at different output ports, thewavelength-band multiplexers comprise a means which multiplexes opticalsignals which have been inputted from the plurality of input ports foreach wavelength band and which outputs a wavelength division multiplexedsignal in which a predetermined number of wavelengths have beenwavelength division multiplexed at the output port, the K×Karrayed-waveguide gratings are provided with a wavelength-routingcharacteristic for each wavelength band of central wavelengthλB₁±wavelength band width Δλ₁, central wavelength λB₂±wavelength bandwidth Δλ₂ (λB₁+αλ₁<λB₂−Δλ₂), central wavelength λB₃±wavelength bandwidth Δλ₃ (λB₂+Δλ₂<λB₃−Δλ₃), . . . central wavelength λB_(R)±wavelengthband width Δλ_(R) (λB_(R−1)+Δλ_(R−1)<λB_(R)−Δλ_(R)), the output ports ofthe wavelength-band demultiplexers which are respectively connected tothe N device input ports are one to one connected to the input ports ofthe K×K arrayed-waveguide gratings which have wavelength-routingcharacteristics at the wavelength bands of the optical signals which areoutputted from the output ports of the wavelength-band demultiplexers,and the output ports of the K×K arrayed-waveguide gratings are one toone connected to the input ports of any one of the plurality ofwavelength-band multiplexers which can multiplex optical signals ofwavelengths which belong to the wavelength bands of the optical signalswhich are outputted from the output ports of the K×K arrayed-waveguidegratings, and each of the communication nodes comprises: a J×1wavelength-band multiplexer, where J being an integer greater than orequal to 2, which has J input ports IP [1], IP [2], IP [3], . . . IP [J]and a single output port, and outputs at the single output port opticalsignals of wavelengths which belong to the wavelength bands of centralwavelength λB₁±wavelength band width Δλ₁, central wavelengthλB₂±wavelength band width Δλ₂, central wavelength λB₃±wavelength bandwidth Δλ₃, . . . , central wavelength λB_(J)±wavelength band widthΔλ_(J), which are inputted to each of the J input ports, whereλB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), for 1=m=J−1, where m being an integer;at least one wavelength-tunable optical light source integrated opticaltransmitter which is connected to any one of the input ports IP [1], IP[2], IP [3], . . . IP [J] of the J×1 wavelength-band multiplexer, whichis provided with a wavelength-tunable optical light source which can beset to a wavelength within a wavelength band which belongs to the inputport which is connected, and which outputs light of the wavelength; aplurality of wavelength division multiplexers which are provided to eachof the input ports of the J×1 wavelength-band multiplexer, other thanthe input port to which the wavelength-tunable optical light sourceintegrated optical transmitter is connected, and which have two or moreinput ports and one output port, with the output port being connected toone of the input ports of the J×1 wavelength-band multiplexer; aplurality of optical transmitters which are connected to the input portsof the wavelength division multiplexer, and which emit light ofwavelength which belongs to a wavelength band of central wavelengthλBm±wavelength band width Δλm; a 1×J wavelength-band demultiplexer,where J being an integer greater than or equal to 2, which has J outputports OP[1], OP[2], OP[3], . . . OP[J] and a single input port, andoutputs at the J output ports optical signals of wavelengths whichbelong to the wavelength band widths of central wavelengthλB₁±wavelength band width Δλ₁, central wavelength λB₂±wavelength bandwidth Δλ₂, central wavelength λB₃±wavelength band width Δλ₃, . . .central wavelength λB_(J)±wavelength band width Δλ_(J), which areinputted to the single input port, whereλB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), for 1=m=J, where m being an integer; anoptical receiver which is connected to that output port, among theoutput ports OP[1], OP[2], OP[3], . . . OP[J] of the 1×J wavelength-banddemultiplexer, which belongs to the wavelength band to which thewavelength-tunable optical light source integrated optical transmitteris provided, and which receives an optical signal of the wavelengthwhich is outputted from the wavelength-tunable optical light sourceintegrated optical transmitter; a plurality of wavelength divisiondemultiplexers which are provided to each of the output ports of the 1×Jwavelength-band demultiplexer, except for the output port to which theoptical receiver is connected, which have two or more output ports and asingle input port, and the input port is connected to one of the outputports of the 1×J wavelength-band demultiplexer; and a plurality ofoptical receivers which are connected to the output ports of thewavelength division demultiplexers, and wherein the single input port ofthe 1×J wavelength-band demultiplexer is connected via an opticalwaveguide to one of the device output ports of the wavelength-routingdevice, and the optical path management method comprises: a step of, ifat least one group of the wavelength-tunable optical light sourceintegrated optical transmitters exists which are provided to all thecommunication nodes and which output optical signals of the samewavelength band, and if there are K wavelength bands, where K being aninteger greater than or equal to 2, which belong to the input ports ofthe J×1 wavelength-band multiplexer which are connected to thewavelength-tunable optical light source integrated optical transmitters,assigning mutually different priority rankings from 1 to K to thewavelength bands which belong to the input ports of the J×1wavelength-band multiplexer which are connected to thewavelength-tunable optical light source integrated optical transmitters;a step of, when, among the wavelength bands which belong to the inputports of the J×1 wavelength-band multiplexer which are connected to thewavelength-tunable optical light source integrated optical transmitter,the highest numbered priority ranking among the wavelength bands forwhich an optical path exists between x-th communication node and y-thcommunication node is number b, and the lowest numbered priority rankingamong the wavelength bands for which an optical path whose start pointis the x-th communication node, an optical path whose end point is thex-th communication node, an optical path whose start point is the y-thcommunication node, and an optical path whose end point is the y-thcommunication node do not exist is number a, and the number a is smallerthan the number b; and controlling ON/OFF and an oscillation wavelengthof the wavelength-tunable optical light source integrated opticaltransmitter so as to establish an optical path between the x-thcommunication node and the y-th communication node upon the wavelengthband of a-th priority ranking; and a step of establishing an opticalpath between the x-th communication node and the y-th communication nodeupon the wavelength band of the a-th priority ranking, and thereaftercontrolling ON/OFF and the oscillation wavelength of thewavelength-tunable optical light source integrated optical transmitterso as to cancel the optical path which was established between the x-thcommunication node and the y-th communication node upon the wavelengthband of b-th priority ranking.

Yet further, the present invention is an optical path management programwhich causes a computer to execute the steps of the above-describedoptical path management method.

Even yet further, the present invention is a recording medium which canbe read by a computer, upon which this optical path management programis recorded.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a figure showing the overall structure of an opticalcommunication system according to the first embodiment according to thepresent invention.

FIG. 2 is a figure for explanation of a wavelength-band demultiplexer ofthe optical communication system according to the first embodimentaccording to the present invention.

FIG. 3 is a figure for explanation of a wavelength-band multiplexer ofthe optical communication system according to the first embodimentaccording to the present invention.

FIG. 4 is a figure showing the relationship between the input and outputports of an arrayed-waveguide grating and wavelengths, for the firstembodiment according to the present invention.

FIG. 5 is a figure showing the relationship between the input and outputports of an arrayed-waveguide grating and wavelength, for the firstembodiment according to the present invention.

FIG. 6 is a figure showing the relationship between the input and outputports of an arrayed-waveguide grating and wavelength, for the firstembodiment according to the present invention.

FIG. 7 is a figure showing the relationship between the input and outputports of an arrayed-waveguide grating and wavelength, for the firstembodiment according to the present invention.

FIG. 8 is a block diagram showing the structure of optical transceiversections of respective communication nodes, in the first embodimentaccording to the present invention.

FIG. 9 is a block diagram for the second embodiment according to thepresent invention, showing a structural example of initial constructionof an optical transceiver section of a communication node.

FIG. 10 is a block diagram for a communication node of the secondembodiment according to the present invention, for explanation of astructural example after increase of an optical transceiver section of adifferent wavelength band.

FIG. 11 is a block diagram for a communication node of the secondembodiment according to the present invention, for explanation of astructural example after increase of an optical transceiver section of adifferent wavelength band.

FIG. 12 is a block diagram showing a structural example of an opticaltransceiver section of a communication node of the third embodimentaccording to the present invention.

FIG. 13 is a block diagram for explanation of the structure of anoptical transceiver section of respective communication nodes of thefourth embodiment according to the present invention.

FIGS. 14A through 14H are block diagrams showing the structure of atransmission module and a reception module in the fourth embodimentaccording to the present invention.

FIG. 15 is a block diagram showing the connection relationship of acontrol device for transceiver and an optical path management device, inthe fourth embodiment according to the present invention.

FIG. 16 is a block diagram showing the structure of an optical pathmanagement device in the fourth embodiment according to the presentinvention.

FIG. 17 is a figure showing an example of a database of an optical pathmanagement device of the fourth embodiment according to the presentinvention.

FIG. 18 is a structural diagram of the fifth embodiment according to thepresent invention.

FIGS. 19A through 19D are explanatory figures showing an example of adatabase in which optical paths of an optical matrix switch is recorded.

FIG. 20 is a flowchart of the processing of the optical path managementdevice of the fifth embodiment according to the present invention.

FIG. 21 is a flowchart of the processing of the optical path managementdevice of the fifth embodiment according to the present invention.

FIG. 22 is a flowchart of the processing of the optical path managementdevice of the fifth embodiment according to the present invention.

FIG. 23 is a structural diagram showing the sixth embodiment accordingto the present invention.

FIG. 24 is a structural diagram showing the seventh embodiment accordingto the present invention.

FIG. 25 is a block diagram showing the structure of a conventionaloptical communication network system based on wavelength path routingwhich is implemented using an arrayed-waveguide grating.

FIG. 26 is a figure showing the relationship between the input andoutput ports of the conventional arrayed-waveguide grating andwavelengths.

FIG. 27 is a figure showing the relationship between the input andoutput ports of the conventional arrayed-waveguide grating andwavelengths.

FIG. 28 is a block diagram showing a structural example of aconventional optical network system which takes advantage of awavelength-band.

FIG. 29 is a block diagram showing another structural example of aconventional optical network system which takes advantage of awavelength-band.

FIG. 30 is a structural diagram showing an example of a conventionaloptical cross connect device.

FIGS. 31A through 31D are explanatory figures showing an example ofoptical paths between input optical fibers and output optical fibers,when the optical paths are not arranged.

FIGS. 32A through 32D are explanatory figures showing an example ofoptical paths between input optical fibers and output optical fibers,when the optical paths are arranged.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following, respective embodiments according to the presentinvention will be explained based upon the figures.

It should be understood that although, in the first through the fourthembodiments according to the present invention, the explanation is madeby taking 4 as the number N of both the device input ports and thedevice output ports of the wavelength-routing device in the opticalcommunication network system according to the present invention, this isnot to be considered as being limiting; provided that N is an integergreater than or equal to 2, this will be acceptable.

The First Embodiment

FIG. 1 is a structural figure showing the optical communication networksystem of the first embodiment according to the present invention. InFIG. 1, 200-1 through 200-4 are communication nodes, 210 is awavelength-routing device, and 250-1 through 250-4 and 260-1 through260-4 are optical transmission lines (optical fibers) which connect thecommunication nodes 200-1 through 200-4 and the wavelength-routingdevice 210.

Furthermore, the wavelength-routing device 210 comprises four deviceinput ports 210-11 through 210-14 and four device output ports 210-21through 210-24, wavelength-band demultiplexers 220-1 through 220-4,wavelength-band multiplexers 230-1 through 230-4, and 4×4arrayed-waveguide gratings 241 through 244.

The communication node 200-1, along with being connected to the firstdevice input port 210-11 of the wavelength-routing device 210 via theoptical transmission line 250-1, is also connected to the first deviceoutput port 210-21 of the wavelength-routing device 210 via the opticaltransmission line 260-1.

The communication node 200-2, along with being connected to the seconddevice input port 210-12 of the wavelength-routing device 210 via theoptical transmission line 250-2, is also connected to the second deviceoutput port 210-22 of the wavelength-routing device 210 via the opticaltransmission line 260-2.

The communication node 200-3, along with being connected to the thirddevice input port 210-13 of the wavelength-routing device 210 via theoptical transmission line 250-3, is also connected to the third deviceoutput port 210-23 of the wavelength-routing device 210 via the opticaltransmission line 260-3.

The communication node 200-4, along with being connected to the fourthdevice input port 210-14 of the wavelength-routing device 210 via theoptical transmission line 250-4, is also connected to the fourth deviceoutput port 210-24 of the wavelength-routing device 210 via the opticaltransmission line 260-4.

Each of the wavelength-band demultiplexers 220-1 through 220-4 comprisesa single input port 221 and four output ports 222-1 through 222-4, andthe input port 221 of the first wavelength-band demultiplexer 220-1 isconnected to the first device input port 210-11. Furthermore, the inputport 221 of the second wavelength-band demultiplexer 220-2 is connectedto the second device input port 210-12, the input port 221 of the thirdwavelength-band demultiplexer 220-3 is connected to the third deviceinput port 210-13, and the input port 221 of the fourth wavelength-banddemultiplexer 220-4 is connected to the fourth device input port 210-14.

Each of the wavelength-band multiplexers 230-1 through 230-4 comprises asingle output port 232 and four input ports 232-1 through 232-4, and theoutput port 232 of the first wavelength-band multiplexer 230-1 isconnected to the first device output port 210-11. Furthermore, theoutput port 232 of the second wavelength-band multiplexer 230-2 isconnected to the second device output port 210-22, the output port 232of the third wavelength-band multiplexer 230-3 is connected to the thirddevice output port 210-23, and the output port 232 of the fourthwavelength-band multiplexer 230-4 is connected to the fourth deviceoutput port 210-24.

It should be understood that each of the wavelength-band demultiplexers220-1 through 220-4 and each of the wavelength-band multiplexers 230-1through 230-4 may, for example, be made using a dielectric multilayerfilter, an optical coupler which is made with an optical fiber, or anoptical coupler which is made with a planar optical waveguide, or thelike.

The 4×4 arrayed-waveguide grating 241 is made, for example, from aquartz type optical waveguide, and, along with having acyclic-wavelength characteristic, also has four input ports 2411-1through 2411-4 and four output ports 2412-1 through 2412-4; and thefirst through the fourth input ports 2411-1 through 2411-4 arerespectively connected in one to one correspondence to the first outputports 222-1 of the first through the fourth wavelength-banddemultiplexers 220-1 through 220-4 in the order described, while thefirst through the fourth output ports 2412-1 through 2412-4 arerespectively connected in one to one correspondence to the first inputports 231-1 of the first through the fourth wavelength-band multiplexers230-1 through 230-4 in the order described.

The 4×4 arrayed-waveguide grating 242 has four input ports 2421-1through 2421-4 and four output ports 2422-1 through 2422-4; and thefirst through the fourth input ports 2421-1 through 2421-4 arerespectively connected in one to one correspondence to the second outputports 222-2 of the first through the fourth wavelength-banddemultiplexers 220-1 through 220-4 in the order described, while thefirst through the fourth output ports 2422-1 through 2422-4 arerespectively connected in one to one correspondence to the second inputports 231-2 of the first through the fourth wavelength-band multiplexers230-1 through 230-4 in the order described.

The 4×4 arrayed-waveguide grating 243 has four input ports 2431-1through 2431-4 and four output ports 2432-1 through 2432-4; and thefirst through the fourth input ports 2431-1 through 2431-4 arerespectively connected in one to one correspondence to the third outputports 222-3 of the first through the fourth wavelength-banddemultiplexers 220-1 through 220-4 in the order described, while thefirst through the fourth output ports 2432-1 through 2432-4 arerespectively connected in one to one correspondence to the third inputports 231-3 of the first through the fourth wavelength-band multiplexers230-1 through 230-4 in the order described.

The 4×4 arrayed-waveguide grating 244 has four input ports 2441-1through 2441-4 and four output ports 2442-1 through 2442-4; and thefirst through the fourth input ports 2441-1 through 2441-4 arerespectively connected in one to one correspondence to the fourth outputports 222-4 of the first through the fourth wavelength-banddemultiplexers 220-1 through 220-4 in the order described, while thefirst through the fourth output ports 2442-1 through 2442-4 arerespectively connected in one to one correspondence to the fourth inputports 231-4 of the first through the fourth wavelength-band multiplexers230-1 through 230-4 in the order described.

Next, the components which make up the wavelength-routing device 210will be explained in detail.

As shown in FIG. 2, the wavelength-band demultiplexer 220 (220-1 through220-4) has a single input port 221 and four output ports 222-1 through222-4, and an optical signal whose wavelength is included in thewavelength band λB₁±Δλ₁ (where λB₁ and Δλ₁ respectively denotewavelengths) is outputted from the first output port 222-1, while anoptical signal whose wavelength is included in the wavelength bandλB₂±Δλ₂ (where λB₂ and Δλ₂ respectively denote wavelengths) is outputtedfrom the second output port 222-2. Furthermore, an optical signal whosewavelength is included in the wavelength band λB₃±Δλ₃ (where λB₃ and Δλ₃respectively denote wavelengths) is outputted from the third output port222-3, while an optical signal whose wavelength is included in thewavelength band λB₄±Δλ₄ (where λB₄ and Δλ₄ respectively denotewavelengths) is outputted from the fourth output port 222-4.

This embodiment employs the wavelength-band demultiplexers 220-1 through220-4 which use dielectric multilayer filters, λB₁=1511 nm, λB₂=1531 nm,λB₃=1551 nm, λB₄=1571 nm, and Δλ₁=Δλ₂=Δλ₃=Δλ₄=9 nm.

As shown in FIG. 3, the wavelength-band multiplexer 230 (230-1 through230-4) has four input ports 231-1 through 231-4 and a single output port232; and: an optical signal whose wavelength is included in thewavelength band λB₁±Δλ₁ (where λB₁ and Δλ₁ respectively denotewavelengths) is inputted to the first input port 231-1; an opticalsignal whose wavelength is included in the wavelength band λB₂±Δλ₂(where λB₂ and Δλ₂ respectively denote wavelengths) is inputted to thesecond input port 231-2; an optical signal whose wavelength is includedin the wavelength band λB₃±Δλ₃ (where λB₃ and αλ₃ respectively denotewavelengths) is inputted to the third input port 231-3; and an opticalsignal whose wavelength is included in the wavelength band λB₄±Δλ₄(where λB₄ and Δλ₄ respectively denote wavelengths) is inputted to thefourth input port 231-4; and the optical signals which have beeninputted to these four input ports 231-1 through 231-4 are multiplexedand are outputted from the output port 232.

This embodiment uses the wavelength-band multiplexers 230-1 through230-4 which use dielectric multilayer filters, λB₁=1511 nm, λB₂=1531 nm,λB₃=1551 nm, λB₄=1571 nm, and Δλ₁=Δλ₂=Δλ₃=Δλ₄=9 nm.

As previously described, the arrayed-waveguide gratings 241 through 244have four input ports and four output ports, and the arrayed-waveguidegrating 241 is one whose wavelength-routing characteristic is designedfor a wavelength which is included in the wavelength band λB₁±αλ₁, andthe relationship between its respective input and output ports and thewavelengths λ11, λ12, λ13, and λ14 is as shown in FIG. 4. Moreover, itis arranged for λ11, λ12, λ13, and λ14 to be mutually different, and forthe relationship λB₁−Δλ₁<λ11, λ12, λ13, λ14<λB₁+Δλ₁ to be satisfied.

The arrayed-waveguide grating 242 is one whose wavelength-routingcharacteristic is designed for a wavelength which is included in thewavelength band λB₂±Δλ₂, and the relationship between its respectiveinput and output ports and the wavelengths λ21, λ22, λ23, and λ24 is asshown in FIG. 5. Moreover, it is arranged for λ21, λ22, λ23, and λ24 tobe mutually different, and for the relationship λB₂−Δλ₂<λ21, λ22, λ23,λ24<λB₂+Δλ₂ to be satisfied.

The arrayed-waveguide grating 243 is one whose wavelength-routingcharacteristic is designed for a wavelength which is included in thewavelength band λB₃±Δλ₃, and the relationship between its respectiveinput and output ports and the wavelengths λ31, λ32, λ33, and λ34 is asshown in FIG. 6. Moreover, it is arranged for λ31, λ32, λ33, and λ34 tobe mutually different, and for the relationship λB₃−Δλ₃<λ31, λ32, λ33,λ34<λB₃+Δλ₃ to be satisfied.

The arrayed-waveguide grating 244 is one whose wavelength-routingcharacteristic is designed for a wavelength in included in thewavelength band λB₄±Δλ₄, and the relationship between its respectiveinput and output ports and the wavelengths λ41, λ42, λ43, and λ44 is asshown in FIG. 7. Moreover, it is arranged for λ41, λ42, λ43, and λ44 tobe mutually different, and for the relationship λB₄−Δλ₄<λ41, λ42, λ43,λ44<λB₄+Δλ₄ to be satisfied.

It should be understood that, in this embodiment, quartz type opticalwaveguide types are used as the arrayed-waveguide gratings 241 through244.

Next, the structure of the communication nodes 200-1 through 200-4 willbe explained.

FIG. 8 is a block diagram showing the structure of the opticaltransceiver section of each of the communication nodes 200-1 through200-4. In FIG. 8, 201 denotes an optical transceiver section, 250denotes an optical transmission line which conducts the optical signalswhich have been outputted from the communication node 200-1 through200-4 to the wavelength-routing device 210, and 260 is an opticaltransmission line which conducts the optical signal which has beenoutputted from the wavelength-routing device 210 to the communicationnodes 200-1 through 200-4.

The optical transceiver section 201 comprises a wavelength-bandmultiplexer 230 which has four input ports and one output port, awavelength-band demultiplexer 220 which has one input port and fouroutput ports, four optical transmission sections 290-1 through 290-4,and four optical reception sections 300-1 through 300-4.

It should be understood that each of the wavelength-band demultiplexer220 and the wavelength-band multiplexer 230 is made using, for example,a dielectric multilayer filter, an optical coupler which is made with anoptical fiber, or an optical coupler which is made with a planar opticalwaveguide, or the like.

The optical transmission line 250 is connected to the output port 230-21of the wavelength-band multiplexer 230, and the optical signal outputfrom the first optical transmission section 290-1 is inputted to thefirst input port 230-11. Furthermore, the optical signal output from thesecond optical transmission section 290-2 is inputted to the secondinput port 230-12 of the wavelength-band multiplexer 230; the opticalsignal output from the third optical transmission section 290-3 isinputted to the third input port 230-13; and the optical signal outputfrom the fourth optical transmission section 290-4 is inputted to thefourth input port 230-14.

The first optical transmission section 290-1 is an optical transmissionsection of the wavelength band λB₁±Δλ₁, and comprises a wavelengthdivision multiplexer 271 which has four input ports 271-11 through271-14 and one output port 271-21, and four optical transmitters 2711-1through 2711-4 which are connected to the input ports 271-11 through271-14. Furthermore, the optical transmitters 2711-1 through 2711-4convert electrical data signals which have been inputted into opticalsignals of respective wavelengths λ11, λ12, λ13, and λ14 and outputsthem.

The second optical transmission section 290-2 is an optical transmissionsection of the wavelength band λB₂±Δλ₂, and comprises a wavelengthdivision multiplexer 272 which has four input ports 272-11 through272-14 and one output port 272-21, and four optical transmitters 2712-1through 2712-4 which are connected to the input ports 272-11 through272-14. Furthermore, the optical transmitters 2712-1 through 2712-4convert electrical data signals which have been inputted into opticalsignals of respective wavelengths λ21, λ22, λ23, and λ24 and outputsthem.

The third optical transmission section 290-3 is an optical transmissionsection of the wavelength band λB₃±Δλ₃, and comprises a wavelengthdivision multiplexer 273 which has four input ports 273-11 through273-14 and one output port 273-21, and four optical transmitters 2713-1through 2713-4 which are connected to the input ports 273-11 through273-14. Furthermore, the optical transmitters 2713-1 through 2713-4convert electrical data signals which have been inputted into opticalsignals of respective wavelengths λ31, λ32, λ33, and λ34 and outputsthem.

The fourth optical transmission section 290-4 is an optical transmissionsection of the wavelength band λB₄±Δλ₄, and comprises a wavelengthdivision multiplexer 274 which has four input ports 274-11 through274-14 and one output port 274-21, and four optical transmitters 2714-1through 2714-4 which are connected to the input ports 274-11 through274-14. Furthermore, the optical transmitters 2714-1 through 2714-4convert electrical data signals which have been inputted into opticalsignals of respective wavelengths λ41, λ42, λ43, and λ44 and outputsthem.

The optical transmission line 260 is connected to the input port 220-11of the wavelength-band demultiplexer 220, and the optical signal whichis outputted from the first output port 220-21 is inputted to the firstoptical reception section 300-1. Furthermore, the optical signal whichis outputted from the second output port 220-22 of the wavelength-banddemultiplexer 220 is inputted to the second optical reception section300-2, the optical signal which is outputted from the third output port220-23 is inputted to the third optical reception section 300-3, and theoptical signal which is outputted from the fourth output port 220-24 isinputted to the fourth optical reception section 300-4.

The first optical reception section 300-1 comprises a wavelengthdivision demultiplexer 281 which comprises one input port 281-11 andfour output ports 281-21 through 281-24, and four optical receivers2811-1 through 2811-4 which are connected to the output ports 281-21through 281-24.

The wavelength division demultiplexer 281 is one whose wavelengthdivision demultiplexing characteristic is designed for a wavelengthwhich is included in the wavelength band λB₁±Δλ₁, and, when opticalsignals of wavelengths λ11, λ12, λ13, and λ14 are inputted to its inputport 281-11, the optical signal of the wavelength λ11 is outputted atthe first output port 281-21, the optical signal of the wavelength λ12is outputted at the second output port 281-22, the optical signal of thewavelength λ13 is outputted at the third output port 281-23, and theoptical signal of the wavelength λ14 is outputted at the fourth outputport 281-24. Furthermore, each of the four optical receivers 2811-1through 2811-4 converts the optical signal which has been inputted intoan electrical signal, and outputs it as a data signal.

The second optical reception section 300-2 comprises a wavelengthdivision demultiplexer 282 which comprises one input port 282-11 andfour output ports 282-21 through 282-24, and four optical receivers2812-1 through 2812-4 which are connected to the output ports 282-21through 282-24.

The wavelength division demultiplexer 282 is one whose wavelengthdivision demultiplexing characteristic is designed for a wavelengthwhich is included in the wavelength band λB₂±Δλ₂, and, when opticalsignals of wavelengths λ21, λ22, λ23, and λ24 are inputted to its inputport 282-11, the optical signal of the wavelength λ21 is outputted atthe first output port 282-21, the optical signal of the wavelength λ22is outputted at the second output port 282-22, the optical signal of thewavelength λ23 is outputted at the third output port 282-23, and theoptical signal of the wavelength λ24 is outputted at the fourth outputport 282-24. Furthermore, each of the four optical receivers 2812-1through 2812-4 converts the optical signal which has been inputted intoan electrical signal, and outputs it as a data signal.

The third optical reception section 300-3 comprises a wavelengthdivision demultiplexer 283 which comprises one input port 283-11 andfour output ports 283-21 through 283-24, and four optical receivers2813-1 through 2813-4 which are connected to the output ports 283-21through 283-24.

The wavelength division demultiplexer 283 is one whose wavelengthdivision demultiplexing characteristic is designed for a wavelengthwhich is included in the wavelength band λB₃±αλ₃, and, when opticalsignals of wavelengths λ31, λ32, λ33, and λ34 are inputted to its inputport 283-11, the optical signal of the wavelength λ31 is outputted atthe first output port 283-21, the optical signal of the wavelength λ32is outputted at the second output port 283-22, the optical signal of thewavelength λ33 is outputted at the third output port 283-23, and theoptical signal of the wavelength λ34 is outputted at the fourth outputport 283-24. Furthermore, each of the four optical receivers 2813-1through 2813-4 converts the optical signal which has been inputted intoan electrical signal, and outputs it as a data signal.

The fourth optical reception section 300-4 comprises a wavelengthdivision demultiplexer 284 which comprises one input port 284-11 andfour output ports 284-21 through 284-24, and four optical receivers2814-1 through 2814-4 which are connected to the output ports 284-21through 284-24.

The wavelength division demultiplexer 284 is one whose wavelengthdivision demultiplexing characteristic is designed for a wavelengthwhich is included in the wavelength band λB₄±Δλ₄, and, when opticalsignals of wavelengths λ41, λ42, λ43, and λ44 are inputted to its inputport 284-11, the optical signal of the wavelength λ41 is outputted atthe first output port 284-21, the optical signal of the wavelength λ42is outputted at the second output port 284-22, the optical signal of thewavelength λ43 is outputted at the third output port 284-23, and theoptical signal of the wavelength λ44 is outputted at the fourth outputport 284-24. Furthermore, each of the four optical receivers 2814-1through 2814-4 converts the optical signal which has been inputted intoan electrical signal, and outputs it as a data signal.

Next, the operation of the optical communication network systemaccording to this first embodiment according to the present inventionwill be explained with reference to FIGS. 1 through 8. Here, by way ofexample, the case in which the communication node 200-1 performs datacommunication with the communication node 200-3 will be explained.

At the communication node 200-1, the optical signal S13-p of thewavelength λp3 which has been outputted from the optical transmitter271p-3 of the optical transmission section 290-p which is included inthe optical transmitter which sends out the optical signal of thewavelength band λB_(p)±Δλ_(p) (where p is an integer variable, and, inthis embodiment, p is 1, 2, 3, or 4, and can take the same value in theexplanation below) is outputted to the optical transmission line 250 viathe wavelength division multiplexer 27p and the wavelength-bandmultiplexer 230.

Furthermore, the optical signal S13-p is transmitted along the opticaltransmission line 250, and arrives at the input port 221 of thewavelength-band demultiplexer 220-1 of the wavelength-routing device 210and is outputted from the output port 222-p.

The optical signal S13-p which has been outputted from the output port222-p is inputted to the first input port 24p1-1 of thearrayed-waveguide grating 24p.

From the relationships between the input and output ports of thearrayed-waveguide grating 24p and wavelengths shown in FIGS. 4 through7, the optical signal S13-p is outputted by the third output port 24p2-3of the arrayed-waveguide grating 24p.

The optical signal S13-p which has been outputted from the third outputport 24p2-3 of the arrayed-waveguide grating 24p is inputted to the p-thinput port 231-p of the wavelength-band multiplexer 230-3, and isoutputted from the output port 232.

The optical signal S13-p which has been outputted from the output port232 of the wavelength-band multiplexer 230-3 is transmitted along theoptical transmission line 260-3, and arrives at the input port 220-11 ofthe wavelength-band demultiplexer 220 of the communication node 200-3.

The optical signal S13-p is outputted from the output port 220-2p of thewavelength-band demultiplexer 220 of the communication node 200-3, isinputted to the wavelength division demultiplexer 28p, is outputted fromthe output port 28p-23 of the wavelength division demultiplexer 28p, andis received by the optical receiver 281p-3.

In this manner, when transmitting data from the communication node 200-1to the communication node 200-3, it is possible to do this by using theoptical signal S13-p of the wavelength λp3 which is sent out from theoptical transmitter 271p-3, which is provided in the opticaltransmission section 290-p of the wavelength band λBp±Δλp of thecommunication node 200-1.

In other words, in this embodiment, it is possible to use the fouroptical paths S13-1, S13-2, S13-3, and S13-4. By doing the same asabove, in this embodiment, it is possible to perform communication viafour optical paths between two communication nodes.

In the above manner, although with this embodiment, just as in theconventional example, the communication nodes 200-1 through 200-4 andthe wavelength-routing device 210 which make up the opticalcommunication system are connected by a pair of optical fibers, in thisembodiment, by arranging the arrayed-wavelength gratings 241 through 244independently in each wavelength band in the wavelength-routing device210, and by performing the wavelength-band multiplexing of wavelengthbands and the wavelength-band demultiplexing of wavelength bands in eachof the communication nodes 200-1 through 200-4 and thewavelength-routing device 210, it is possible to establish a singleoptical path between the communication nodes for each wavelength band.

Accordingly, although in the conventional example it was possible toestablish only a single optical path between the communication nodeswith one pair of optical fibers, by utilizing the structure of thisembodiment, it is possible to establish, at maximum, the same number ofoptical paths as wavelength bands, and thus it is possible to increasethe transmission capacity between the communication nodes in an easymanner.

The Second Embodiment

Next, the second embodiment according to the present invention will beexplained.

As has already been explained with regard to the first embodiment,although it is possible to establish four optical paths using fourwavelength bands (the wavelength band λB₁±Δλ₁, the wavelength bandλB₂±Δλ₂, the wavelength band λB₃±Δλ₃, and the wavelength band λB₄±Δλ₄),in the initial construction of an optical communication network system,as shown in FIG. 9, it is possible to provide an optical transmissionsection and an optical reception section of the single wavelength bandλB_(p)±Δλ_(p) (where p is an integer variable, and p is any one of 1, 2,3, and 4) to each of the communication nodes 200-1 through 200-4, andthus to increase the wavelength bands according to the transmissioncapacity between the communication nodes (in FIG. 9, by way of example,the case of p=1 is shown).

For example, FIG. 10 is an example in which another optical transmissionsection 290-2 and another optical reception section 300-2 of a furtherwavelength band have been added to each of the communication nodes 200-1through 200-4 of the second embodiment shown in FIG. 9. By doing this,two optical paths are established between the respective communicationnodes.

Yet further, although in FIG. 10 an optical transceiver section for awavelength band was added to all of the communication nodes 200-1through 200-4, it would also be possible to add a wavelength band onlybetween those communication nodes for which it is desired to add acommunication band. For example, an initial optical communicationnetwork structure may be supposed which is made up from thecommunication node 200-1 through the communication node 200-4 as shownin FIG. 9, and each of the communication nodes 200-1 through 200-4 hasestablished an optical path at the wavelength band λB₁±Δλ₁ forperforming communication.

Subsequently, if an additional communication band (an optical path)between the communication node 200-1 and the communication node 200-3has become necessary, it would be acceptable to add, only to thecommunication node 200-1 and to the communication node 200-3, theoptical transmission section 290-2 and the optical reception section300-2 of the wavelength band λB_(p)±Δλ_(p) in which only the opticaltransmitter 2712-3 and the optical receiver 2812-3 which are necessaryfor communication between the communication node 200-1 and thecommunication node 200-3 are implemented as shown in FIG. 11. It shouldbe understood that, in FIG. 11, by way of example, the case p=2 isshown.

The Third Embodiment

Next, the third embodiment according to the present invention will beexplained with reference to FIG. 12. It should be understood that, inFIG. 12, to structural elements which are the same as in the firstembodiment described above, the same reference symbols are affixed, andtheir explanation will be curtailed. In this embodiment, for each of thecommunication nodes 200-1 through 200-4, wavelength-tunable opticallight source integrated optical transmitters 400-1 and 400-2 areimplemented in the optical transmission section 290-2 and the opticaltransmission section 290-3, respectively, and moreover optical receivers500-1 and 500-2 are implemented in the optical reception section 300-2and the optical reception section 300-3, respectively.

The output port of the wavelength-tunable optical light sourceintegrated optical transmitter 400-1 is connected to the input port230-12 of the wavelength-band multiplexer 230, while the output port ofthe wavelength-tunable optical light source integrated opticaltransmitter 400-2 is connected to the input port 230-13 of thewavelength-band multiplexer 230.

The wavelength-tunable optical light source integrated opticaltransmitter 400-1 can output light of the wavelengths λ21, λ22, λ23, andλ24 belonging to the wavelength band λB₂±Δλ₂, and moreover thewavelength-tunable optical light source integrated optical transmitter400-2 can output light of the wavelengths λ31, λ32, λ33, and λ34belonging to the wavelength band λB₃±Δλ₃.

Furthermore, the input port of the optical receiver 500-1 is connectedto the output port 220-22 of the wavelength-band demultiplexer 220,while the input port of the optical receiver 500-2 is connected to theoutput port 220-23 of the wavelength-band demultiplexer 220.

Accordingly, each of the communication nodes 200-1 through 200-4 canincrease the number of the optical paths by setting the wavelengths ofthe optical signals which are outputted from the wavelength-tunableoptical light source integrated optical transmitters 400-1 and 400-2 tovalues for routing the optical signals to the communication nodes forwhich it is required to establish optical paths by thewavelength-routing device 210.

Specifically, if the communication node 200-1 performs communicationwith the communication node 200-3 by using an optical signal of awavelength which belongs to the wavelength band λB₂±Δλ₂, the wavelengthof the optical signal S13-2 which is outputted from thewavelength-tunable optical light source integrated optical transmitter400-1 of the communication node 200-1 is set to λ23. This optical signalS13-2 is routed by the wavelength-routing device 210, and is received bythe optical receiver 500-1 of the communication node 200-3. Furthermore,if the communication node 200-1 performs communication with thecommunication node 200-4 by using an optical signal of a wavelengthwhich belongs to the wavelength band λB₃±Δλ₃, the wavelength of theoptical signal S14-3 which is outputted from the wavelength-tunableoptical light source integrated optical transmitter 400-2 of thecommunication node 200-1 is set to λ34. This optical signal S14-3 isrouted by the wavelength-routing device 210, and is received by theoptical receiver 500-2 of the communication node 200-4.

As described above, by providing an optical transmission section whichis equipped with a wavelength-tunable optical light source integratedoptical transmitter in the communication nodes 200-1 through 200-4, itbecomes possible to flexibly select a communication node whichcommunicates in a wavelength band to which the optical transmissionsection belongs.

As the above-described wavelength-tunable optical light sourceintegrated optical transmitters 400-1 and 400-2, it is possible to use,for example, a distributed feedback semiconductor laser, or a multielectrode distributed reflector semiconductor laser, or the like.Furthermore, for a distributed feedback semiconductor laser, byequipping it with a means for varying its temperature, it is possible tovary the wavelength of the optical signal which is output from thesemiconductor laser according to its temperature; while, with a multielectrode distributed reflector semiconductor laser, by equipping itwith a means for varying the value of the energizing electrical current,it is possible to vary the wavelength of the optical signal which isoutput from the semiconductor laser according to the value of thecurrent flow.

It should be understood that the above-described embodiment is no morethan a concrete example of the present invention, and that the presentinvention is not limited only to the structure of the above-describedembodiment. For example, although in the above-described embodiment theexplanation was made by taking, by way of example, both the number ofcommunication nodes and the number N of device input ports and deviceoutput ports of the wavelength-routing device as being 4, this is not tobe considered as being limitative; it goes without saying that any valueof N will be acceptable, provided that it is an integer greater than orequal to 2.

The Fourth Embodiment

Next, the fourth embodiment according to the present invention will beexplained with reference to FIG. 13. It should be understood that, inFIG. 13, to structural elements which are the same as in the firstembodiment described above, the same reference symbols are affixed, andtheir explanation will be curtailed. In this embodiment, for each of thecommunication nodes 200-1 through 200-4, transmission modules 310 areimplemented in the optical transmission section 290-a (where a is aninteger from 1 through 4), and reception modules 311 are implemented inthe optical reception section 300-a.

The structures of the transmission modules 310 and the reception modules311 are shown in FIGS. 14A through 14H.

In FIGS. 14A through 14H, 301 are optical transmitters, 302 is awavelength division multiplexer, 303 is a wavelength divisiondemultiplexer, 304 are optical receivers, 305 are wavelength-tunableoptical light source integrated optical transmitters, 306 is an opticalcoupler, 307 are wavelength-tunable filters, and 308 is an opticalsplitter. There are four types of transmission modules 310-1 through310-4, and there are four types of reception modules 311-1 through311-4.

In the following, the structures of the transmission modules from 310-1through 310-4 and of the reception modules from 311-1 through 311-4 willbe explained in detail.

In the transmission module 310-1, two or more streams of transmitteddata are converted into optical signals of wavelengths which aredetermined by respectively different optical transmitters 301, and theseare wavelength division multiplexed and are outputted by the wavelengthdivision multiplexer 302. In the reception module 311, the wavelengthdivision multiplexed optical signals which have been inputted aredemultiplexed by wavelength by the wavelength division demultiplexer303, and are converted into received signals by the respective opticalreceivers 304. In the subsequent discussion, the combination of thistransmission module 310-1 and this reception module 311-1 will be termeda first transceiving module. It should be understood that, in this firsttransceiving module, according to requirements, it will also beacceptable to reduce the number of the optical transmitters 301 and theoptical receivers 304.

In the transmission module 310-2, a single stream of transmitted data isconverted into an optical signal of a wavelength determined by theoptical transmitter 301, and is outputted. In the reception module311-2, the optical signal of a single wavelength which is inputted isconverted by the optical receiver 304 into a received signal. In thesubsequent discussion, the combination of this transmission module 310-2and this reception module 311-2 will be termed a second transceivingmodule.

In the transmission module 310-3, a single stream of transmitted data isconverted into an optical signal of a wavelength which is determined bythe wavelength-tunable optical light source integrated opticaltransmitter 305, and is outputted. In the reception module 311-3, theoptical signal of a single wavelength which is inputted is converted bythe optical receiver 304 into a received signal. In the subsequentdiscussion, the combination of this transmission module 310-3 and thisreception module 311-3 will be termed a third transceiving module.

In the transmission module 310-4, two or more streams of transmitteddata are converted into optical signals of respectively differentwavelengths which are determined by the N (where N is an integer greaterthan or equal to 2) wavelength-tunable optical light source integratedoptical transmitters 305, and are combined by the optical coupler 306and are outputted. In the reception module 311-4, the multiplexedoptical signal of N or fewer wavelengths which is inputted isdistributed into N routes by the optical splitter 308. These distributedoptical signals are made into an optical signal of a single wavelengthby the wavelength-tunable filters 307 each of which only transmits asignal of a single wavelength, and are respectively converted intoreceived signals by the optical receivers 304. In FIGS. 14G and 14H thecase is shown in which N is 4, but the value of N is not to beconsidered as being limited by this. In the subsequent discussion, thecombination of this transmission module 310-4 and this reception module311-4 will be termed a fourth transceiving module.

In this embodiment, at an optical transmission section 290-a (where a isan integer from 1 through 4) and an optical reception section 300-a ofeach communication node which send and receive signals of the samewavelength band, either any one of the first through the fourthtransceiving modules may be provided, or alternatively none may beprovided. In these cases, it is not absolutely necessary for thetransceiving module at another communication node which transmits andreceives signals of the same wavelength band to be the same.

FIG. 15 is a figure showing the structure of the control system whichperforms the control of this embodiment. In this figure, 211-1 through211-4 are control devices for transceiver, 213 is an optical pathmanagement device, 214 is a communication circuit (network), 200-1through 200-4 are communication nodes, 220-1 through 220-4 arewavelength-band demultiplexers, 230-1 through 230-4 are wavelength-bandmultiplexers, and 241, 242, 243 and 244 are 4×4 arrayed-waveguidegratings.

The control devices for transceiver 211-1 through 211-4 are connected tothe four communication nodes 200-1 to 200-4, and perform control of theoptical transceiving modules. This control of the optical transceivingmodules is performed based upon control signals which are received fromthe optical path management device 213. A drive signal or a stop signalis transmitted to the optical transmitter 301 which is to be the objectof control, a drive signal, a stop signal, or an output wavelengthcontrol signal is transmitted to the wavelength-tunable optical lightsource integrated optical transmitter 305, a transmission wavelengthband control signal is transmitted to the wavelength-tunable filters307, and thereby the optical transceiving module is controlled.

The optical path management device 213 performs management of theoptical path which will be described hereinafter. In order to do this,the optical path management device 213 is connected with the controldevices for transceiver 211-1 through 211-4 via the communicationcircuit 214, and sends and receives control signals to and from them.The internal structure of this optical path management device 213 isshown in FIG. 16. Mainly, this optical path management device 213 ismade up from a processor section 3010, a storage medium 3030, and acontrol signal input-output interface 3020. In this embodiment memory isutilized as the storage medium, but anything may be used as the storagemedium, provided that information can be read from it and written to it.

In the optical path management device 213, databases which maintain thetypes of the transceiving modules which are implemented at eachcommunication node, and the states of the optical transmitters withinthe transceiving modules, the wavelength-tunable optical light sourceintegrated optical transmitters, and the wavelength-tunable filters areheld in the storage medium 3030.

When additionally providing or canceling a path between communicationnodes based upon these databases with the optical path management device213, it is decided by the processor section 3010 which of the opticaltransmitters, wavelength-tunable optical light source integrated opticaltransmitters, and wavelength-tunable filters at each of thecommunication nodes should be controlled or not. The results of thesedecisions are transmitted via the control signal input-output interface3020 to the control devices for transceiver 211-1 through 211-4 ascontrol signals, and controls the optical transceiving modules so as tobe able to additionally provide or to cancel the desired optical path.Furthermore, the optical path management device 213, for each wavelengthband, creates and maintains a database in which the optical pathsbetween communication nodes are recorded.

FIG. 17 shows an example of a database, in which a table is shown whichrelates to the wavelength band λB₁±Δλ₁. It should be understood that, inFIG. 17, “TLD” means a wavelength-tunable optical light source (TunableLaser Diode).

Each row of the database corresponds to a respective one of thecommunication nodes, and maintains the state of the transmitters whichare included in the communication node. In FIG. 17, the first rowcorresponds to the communication node 200-1, the second row correspondsto the communication node 200-2, the third row corresponds to thecommunication node 200-3, and the fourth row corresponds to thecommunication node 200-4.

Each column of the database maintains information which is related tothe optical transmitters of the respective communication nodes.

The fifth column of the database maintains the types of the transceivingmodules which are implemented at the communication nodes. In FIG. 17,the case is shown in which a first transceiving module is implemented atthe communication node 200-1, a second transceiving module isimplemented at the communication node 200-2, a third transceiving moduleis implemented at the communication node 200-3, and a fourthtransceiving module is implemented at the communication node 200-4.

The sixth column maintains the numbers of the wavelength-tunable opticallight source integrated optical transmitters which are implemented atthe communication nodes. In FIG. 17, the case is shown in which nowavelength-tunable optical light source integrated optical transmittersare implemented at the communication node 200-1 and at the communicationnode 200-2, while a single wavelength-tunable optical light sourceintegrated optical transmitter is implemented at the communication node200-3, and two wavelength-tunable optical light source integratedoptical transmitters are implemented at the communication node 200-4.

The seventh column maintains, among the wavelength-tunable optical lightsource integrated optical transmitters which are implemented at thecommunication nodes, the number thereof which are actually being used.In FIG. 17, the case is shown in which no wavelength-tunable opticallight source integrated optical transmitters are being used at thecommunication node 200-1 and at the communication node 200-2, onewavelength-tunable optical light source integrated optical transmitteris being used at the communication node 200-3, and onewavelength-tunable optical light source integrated optical transmitteris being used at the communication node 200-4.

The upper entries in the first through the fourth columns maintain theoptical wavelengths for transmitting signals to the respectivecommunication nodes 200-1, 200-2, 200-3, and 200-4, while the lowerentries therein maintain the states of the optical transmitters forsending signals to these respective communication nodes 200-1, 200-2,200-3, and 200-4. If a first or a second transceiving module isimplemented, the state of the optical transmitter which is maintainedshown in the lower entries is one of: “NA” which shows the state inwhich no optical transmitter which sends a signal to the relevantcommunication node is implemented; or “OFF” which shows the state inwhich an optical transmitter which sends a signal to the relevantcommunication node is implemented but is not being used; or “ON” whichshows the state in which an optical transmitter which sends a signal tothe relevant communication node is implemented and is being used.Furthermore, if a third or a fourth transceiving module is implemented,it is one of “OFF” which shows the state in which no wavelength-tunableoptical light source integrated optical transmitter which sends anoptical signal at a wavelength which sends a signal to the relevantcommunication node exists, or the “number of the wavelength-tunableoptical light source integrated optical transmitter”, which shows that awavelength-tunable optical light source integrated optical transmitterexists which sends an optical signal at a wavelength which sends asignal to the relevant communication node, and which specifies therelevant wavelength-tunable optical light source integrated opticaltransmitter.

In the management of the optical paths between the communication nodes,the optical path management device 213 refers to and changes thedatabase when establishing a new optical path between communicationnodes and when stopping an already existing optical path betweencommunication nodes, and controls the control devices for transceiver211-1 through 211-4 via the communication circuit 214.

First, the operation of the optical path management device 213 when anoptical path is newly established between a communication node 200-x anda communication node 200-y (where both x and y are integers greater thanor equal to 1 and less than or equal to 4). Here, one example of thetrigger for establishment of an optical path between the communicationnode 200-x and the communication node 200-y is an explicit command foroptical path establishment via input from the operator of this system toa console not shown in the figures which is connected to the opticalpath management device 213. Furthermore, another example of such triggeris that the optical path management device receives monitor informationof communication traffic within the system, and that it decides toestablish a new optical path between the communication nodes based uponthis information.

The optical path management device 213 searches, from among the fourdatabases which are provided for each of the wavelength bands, adatabase in which, for both the x-th row and the y-th row, the entry inthe fifth column is “1” or “2”, or the entry in the fifth column is “3”or “4” and the entry in the sixth column is greater than the entry inthe seventh column. Next, within the applicable databases, it searchesfor the databases in which the lower entries both in the x-th row andthe y-th column and in the y-th row and the x-th column are “OFF”. Ifthe result of this search is that a plurality of databases areapplicable, then it obtains its search results based upon some type ofpriority ranking; for example, based upon a priority ranking in which adatabase which corresponds to a shorter wavelength band is accordedpriority.

The optical path management device 213, along with transmitting acommand for establishing an optical path between the communication node200-x and the communication node 200-y upon the wavelength band whichcorresponds to the database which was obtained as the result of thesearch via the communication circuit 214 to the control devices fortransceiver 211-x and 211-y, also updates the database.

The signal which is transmitted to the control device for transceiver211-x will now be explained in concrete terms by way of an example. Ifthe communication node 200-x is implemented with the first or the secondtransceiving module, then a signal is transmitted for creating a drivesignal for the optical transmitter 301 which outputs the wavelengthwhich is maintained in the upper entry of the x-th row and the y-thcolumn of the database. At the same time, “ON” is written into the lowerentry of the x-th row and the y-th column of the database. If thecommunication node 200-x is implemented with the third transceivingmodule, a signal is transmitted for creating a transmission wavelengthsetting signal which sets the wavelength which is outputted by thewavelength-tunable optical light source integrated optical transmitter305 to the wavelength which is maintained in the upper entry of the x-throw and the y-th column of the database. At the same time, a signal istransmitted for creating a drive signal for the wavelength-tunableoptical light source integrated optical transmitter 305. Furthermore, atthe same time, “1” is written into the lower entry of the x-th row andthe y-th column of the database, and “1” is written into the seventh rowentry. If the communication node 200-x is implemented with the fourthtransceiving module, a signal is transmitted for creating a transmissionwavelength setting signal which sets the wavelength which is outputtedby the wavelength-tunable optical light source integrated opticaltransmitter 305 of the lowest number among the ones of thewavelength-tunable optical light source integrated optical transmitters305 which are unused to the wavelength which is maintained in the upperentry of the x-th row and the y-th column of the database. At the sametime, a signal is transmitted for creating a drive signal for thewavelength-tunable optical light source integrated optical transmitter305. Moreover, a signal is transmitted for creating a transmissionwavelength band control signal which sets the transmission wavelengthband of the wavelength-tunable filter 307 which is paired with thewavelength-tunable optical light source integrated optical transmitter305 to the wavelength which is maintained in the upper entry of the x-throw and the y-th column of the database. At the same time as the abovetasks, the number of the wavelength-tunable optical light sourceintegrated optical transmitter which has been driven is written into thelower entry in the x-th row and the y-th column of the database, and 1is added to the seventh row entry.

It should be understood that, when searching the databases, if noapplicable database exists, the fact that it is not possible to add anoptical path is transmitted to the source of the request.

Next, the operation of the optical path management device 213 will beexplained when a requirement has arisen to cancel the optical pathbetween a communication node 200-xx and a communication node 200-yy(where xx and yy are both integers which are greater than or equal to 1and less than or equal to 4) between which an optical path is alreadyestablished. Here, one example of the trigger for cancellation of theoptical path between the communication node 200-xx and the communicationnode 200-yy is an explicit command for optical path cancellation viainput from the operator of this optical communication network system toa console not shown in the figures which is connected to the opticalpath management device 213. Furthermore, another example of such triggeris that the optical path management device receives monitor informationof communication traffic within the system, and that it decides tocancel the new optical path between the communication nodes based uponthis information.

The optical path management device 213 searches, from among the fourdatabases which are provided for each of the wavelength bands, adatabase in which the lower entry in the xx-th row and the yy-th columnand the lower entry in the yy-th row and the xx-th column are both “ON”or both of them are the number of wavelength-tunable optical lightsource integrated optical transmitters. If the result of this search isthat a plurality of databases are applicable, then it obtains its searchresults based upon some type of priority ranking; for example, basedupon a priority ranking in which a database which corresponds to ashorter wavelength band is accorded priority.

The optical path management device 213, along with transmitting acommand for canceling the optical path between the communication node200-xx and the communication node 200-yy upon the wavelength band whichcorresponds to the database which was obtained as the result of thesearch via the communication circuit 214 to the control devices fortransceiver 211-xx and 211-yy, also updates the database.

The signal which is transmitted to the control device for transceiver211-xx will now be explained in concrete terms by way of an example. Ifthe communication node 200-xx is implemented with the first or thesecond transceiving module, a signal is transmitted for creating acancellation signal for the optical transmitter 301 which outputs thewavelength which is maintained in the upper entry of the xx-th row andthe yy-th column of the database. At the same time, “OFF” is writteninto the lower entry of the xx-th row and the yy-th column of thedatabase. If the communication node 200-xx is implemented with the thirdtransceiving module, a signal is transmitted for creating a cancellationsignal for the wavelength-tunable optical light source integratedoptical transmitter 305. At the same time, “OFF” is written into thelower entry in the xx-th row and the yy-th column of the database, and“0” is written into the seventh row. If the communication node 200-x isimplemented with the fourth transceiving module, a signal is transmittedfor creating a cancellation signal for the wavelength-tunable opticallight source integrated optical transmitter 305 whose number is writtenin the lower entry in the xx-th row and the yy-th column of thedatabase. At the same time, “OFF” is written into the lower entry in thexx-th row and the yy-th column of the database, and 1 is subtracted fromthe seventh row entry.

It should be understood that, when searching the databases, if noapplicable database exists, the fact that it is not possible to cancelthe optical path is transmitted to the source of the request.

It is possible to manage the optical paths between the communicationnodes by doing as described above. It should be understood that themanagement method for the optical paths between the communication nodesneed not absolutely necessarily be according to this embodiment; anymethod which is able to implement the same functions will be acceptable,and such a method is also to be considered as being included within thescope of the present invention.

For example, it would also be acceptable to implement the function ofthe optical path management device 213 in any one of the control devicesfor transceiver 211-1 through 211-4, and to omit the optical pathmanagement device 213.

Next, the theory of the optimal wavelength control and management methodof an optical path which are applied to this embodiment will beexplained in detail with reference to examples according to the fifththrough seventh embodiments.

It should be understood that here the objects which are taken forcontrol and management are the wavelength-tunable optical light sourceintegrated optical transmitters 400-1 and 400-2. Attention is directedto the wavelength bands with which the wavelength-tunable optical lightsource integrated optical transmitters 400-1 and 400-2 are equipped, inother words to the wavelength bands λB₂±Δλ₂ and λB₃±Δλ₃. That is, for atleast the wavelength bands which are the objects of control andmanagement, it is presupposed that all of the communication nodes areprovided with wavelength-tunable optical light source integrated opticaltransmitters. To put it in another manner, with regard to the wavelengthbands which are not the objects of control and management, there is nospecific constraint on optical transmitters and optical receivers whichare provided in the respective communication nodes. For this reason, itis not necessary for the structures of the transmitters and thereceivers to be the same at all of the communication nodes.

Furthermore, in this explanation of the theory, each of the wavelengthbands λB₂±Δλ₂ and λB₃±Δλ₃ is treated as a single wavelength, and thewavelength-band demultiplexer 220 and the wavelength-band multiplexer230 are respectively treated as a wavelength division demultiplexingcircuit 1 and a wavelength division multiplexing circuit 2. Yet further,the 4×4 arrayed-waveguide gratings 241 through 244 are treated asoptical matrix switches 3 and 6. At this time, controlling thewavelengths transmitted by the wavelength-tunable optical light sourceintegrated optical transmitters 400-1 and 400-2 within the correspondingwavelength bands corresponds to controlling the optical paths of thematrix switches in the following explanation.

The Fifth Embodiment

FIG. 18 is a figure showing the fifth embodiment according to thepresent invention. In this figure, 1-1, 1-2, . . . 1-N are wavelengthdivision demultiplexing circuits, 2-1, 2-2, . . . 2-N are wavelengthdivision multiplexing circuits, 3-1, 3-2, . . . 3-m are optical matrixswitches, 4-1, 4-2, . . . 4-N are input optical fibers, 5-1, 5-2, . . .5-N are output optical fibers, 11-1, 11-2, . . . 11-N are controldevices for transceiver, 12 is an optical matrix switch control device,13 is an optical path management device, and 14 is a communicationcircuit (a network).

Here, although it is possible to utilize a circuit which employs anarrayed-waveguide grating or a dielectric multilayer filter as thewavelength division demultiplexing circuit and the wavelength divisionmultiplexing circuit, the particular method by which they areimplemented is of no importance, provided that the same functions areimplemented. Furthermore although, as the optical matrix switches, it ispossible to employ optical switches which use the thermo-optic effect,waveguide type switches, MEMS optical switches, bubble optical switches,N input N output arrayed-waveguide gratings, or the like, the particularmethod by which they are implemented is of no importance, provided thatthe same functions are implemented. Yet further, the particular methodby which the entire structure is implemented is of no importance,provided that the same input and output characteristics are implemented.

The control devices for transceiver 11-1 through 11-N are respectivelyconnected to transceivers (not shown in the figures) of N communicationnodes, and they perform control of the wavelength and the like of theoptical signals which are transmitted and received by thesetransceivers.

The optical matrix switch control device 12 is connected to the opticalmatrix switches 3-1 through 3-N, and performs control of the opticalpaths between the input and output ports of each of the optical matrixswitches 3-1 through 3-N.

The optical path management device 13 is connected to the controldevices for transceiver 11-1 through 11-N and to the optical matrixswitch control device 12 via the communication circuit 14, and performstransmission and reception of information signals and management of theoptical path based upon the present invention, as will be describedhereinafter.

In the following, the optical path management method of the presentinvention will be explained by taking, as an example, the case in whichthe number of input optical fibers and output optical fibers is 8, andthe number of multiplexed wavelengths is 4. However, the scale of theoptical communication network system to which the present invention canbe applied is not to be considered as being limited by this.

Based upon the numbers of the input optical fibers and the outputoptical fibers and the number of multiplexed wavelengths, four 8-input8-output optical matrix switches are provided in the opticalcommunication network system. It will be supposed that numbers 1 through4 are appended to these four optical matrix switches which specify theirrespective mutually differing priority rankings, and furthermore thatnumbers 1 through 8 are appended to the groups of a communication node,an input optical fiber along which passes the output signal of thecommunication node, an input port of the optical matrix switch which isconnected to the input optical fiber, the output optical fiber alongwhich passes an input signal to the communication node, and an outputport of the optical matrix switch which is connected to the outputoptical fiber.

The optical path management device 13 creates and maintains a database(not shown in the figures) in which the optical paths for each of theoptical matrix switches are recorded.

FIGS. 19A through 19D are figures showing an example of the databasewhich consists of tables which respectively correspond to the fouroptical matrix switches.

In these four tables, the number in the first row specifies the priorityranking of the optical matrix switch, while the number in the secondcolumn specifies the number of the destination communication node of theoptical path which is established between the destination communicationnode and the communication node specified by the number of the firstcolumn via the optical matrix switch. Furthermore, here, forcommunication nodes which are not used in the relevant optical matrixswitches, “0” is recorded as the number of the destination communicationnode of the optical path.

In the management of the optical paths between the input optical fibersand the output optical fibers (between the input communication nodes andthe destination communication nodes of the optical path), it becomesnecessary to refer to and to change the database when establishing a newoptical path, when canceling an already existing optical path, and whenchanging over an optical path between the optical matrix switches.

First, the operation of the optical path management device 13 will beexplained when a requirement has arisen newly to establish an opticalpath between the xx-th communication node and the yy-th communicationnode.

The flow of the processing of the optical path management device whenestablishing a new optical path as described above is shown in FIG. 20.

The optical path management device 13 searches in the database for anoptical matrix switch which is not in use by both the xx-thcommunication node and the yy-th communication node in the order fromthe data which corresponds to the optical matrix switch which has thepriority ranking whose number is the lowest (in the step S1). Forexample, in the state of the databases shown in FIGS. 19A through 19D,if a requirement has arisen newly to establish an optical path betweenthe communication node 3 and the communication node 4, the secondoptical matrix switch whose priority ranking number is the smallest isobtained as the search result, from among the optical matrix switcheswhich are not used by both the communication node 3 and thecommunication node 4.

When a search result is obtained (YES in the step S2), the optical pathmanagement device 13 transmits (in the step S3) a command for newlyestablishing an optical path according to the search result to thecontrol devices for transceiver 11 of the xx-th communication node andof the yy-th communication node and the optical matrix switch controldevice 12, via the communication circuit 14, here, it transmits acommand to execute communication by an optical signal of the wavelengthλ2 to the control devices for transceiver of the communication node 3and of the communication node 4, and it causes an optical path to beestablished in the optical matrix switch control device 12 between thethird input port and the fourth output port of the second optical matrixswitch, and moreover, along with transmitting the command to cause anoptical path to be established between the fourth input port and thethird output port, it registers the optical path which has newly beenestablished in the database (in the step S4), here, writes 4 as thedestination communication node of the optical path of the inputcommunication node 3 in the table which corresponds to the secondoptical matrix switch, and writes 3 as the destination communicationnode of the optical path of the input communication node 4.

Next, the operation of the optical path management device 13 will beexplained, when the necessity for an optical path which is alreadyestablished between the xxx-th communication node and the yyy-thcommunication node has ceased.

The flow of the processing of the optical path management device whencanceling an already existing optical path as described above is shownin FIG. 21.

The optical path management device 13 searches in the database, for anoptical matrix switch which establishes an optical path between thexxx-th communication node and the yyy-th communication node in the orderfrom the data which corresponds to the optical matrix switch which hasthe priority ranking whose number is the highest (in the step S11). Forexample if, in the state of the databases shown in FIGS. 19A through19D, the optical path between the communication node 1 and thecommunication node 3 has become unnecessary, the fourth optical matrixswitch whose priority ranking number is the highest is the searchresult, among the optical matrix switches which establish optical pathsbetween the communication node 1 and the communication node 3.

When a search result is obtained (YES in the step S12), the optical pathmanagement device 13 transmits (in the step S13) a command for cancelingan optical path according to the search result to the control-devicesfor transceiver 11 of the xxx-th communication node and of the yyy-thcommunication node and the optical matrix switch control device 12, viathe communication circuit 14; here, it transmits a command to stopcommunication by an optical signal of the wavelength λ4 to the controldevices for transceiver of the communication node 1 and of thecommunication node 3, and it causes the optical path in the opticalmatrix switch control device 12 between the first input port and thethird output port of the fourth optical matrix switch to be cancelled,and moreover, along with transmitting the command to cause the opticalpath to be cancelled between the third input port and the first outputport, it deletes the optical path which has been cancelled from thedatabase (in the step S14), here, writes 0 as the destinationcommunication node of the optical path of the input communication node 1in the table which corresponds to the fourth optical matrix switch, andwrites 0 as the destination communication node of the optical path ofthe input communication node 3.

Next, the operation of the optical path management device 13 whenchanging over an optical path between the optical matrix switches willbe explained.

The flow of the processing of the optical path management device whenchanging over an optical path between the optical matrix switches asdescribed above is shown in FIG. 22.

The optical path management device 13 searches, in an order which isdetermined in advance for all the combinations of x and y, the number bof the one of the highest priority ranking among the optical matrixswitches which establish optical paths between the x-th communicationnode and the y-th communication node, and the number a of the one of thelowest priority ranking among the optical matrix switches which does notuse the x-th communication node and the y-th communication node, andextracts the combinations of x, y, a, and b for which the number a issmaller than the number b (in the step S21). For example, in the stateof the database shown in FIGS. 19A through 19D, it extracts (x, y, a,b)=(2, 5, 1, 2), (2, 8, 1, 3), and (1, 3, 2, 4).

Next, if the search result as now described is obtained (YES in the stepS22), the optical path management device 13, if there is one combinationwhich has thus been extracted (NO in the step S23), selects it, while,if there are several (YES in the step S23), selects any one thereof (inthe step S24), and performs changing over of the optical path.

In other words, it transmits a command for newly establishing an opticalpath between the x-th communication node and the y-th communication nodevia the a-th optical matrix switch of the selected group to the controldevices for transceiver 11 of the x-th communication node and of they-th communication node and the optical matrix switch control device 12via the communication circuit 14 (in the step S25). Subsequently, ittransmits a command for canceling the optical path between the x-thcommunication node and the y-th communication node via the b-th opticalmatrix switch of the selected group to the control devices fortransceiver 11 of the x-th communication node and of the y-thcommunication node and the optical matrix switch control device 12 viathe communication circuit 14 (in the step S26). Next, it updates thedatabase; in other words, along with registering the optical path whichhas newly been established in the database, it also deletes from thedatabase the optical path which has been cancelled (in the step S27).

At this time, the reason for first establishing the optical path via thea-th optical matrix switch is in order not to interrupt the optical pathbetween the communication node x and the communication node y.

When the changing over of the optical path has ended, the combinationsof (x, y, a, b) which meet the previously described conditions are againextracted, and changing over of the optical path is performed. This taskis repeated until no combinations of (x, y, a, b) which meet thepreviously described conditions come to be extracted.

It should be understood that, a state in which the optical paths are notarranged will not be generated only by establishing a new optical pathwith the above-described method. However, it is desirable to performchanging over of the optical paths between the optical matrix switchesafter cancellation of an already existing optical path, since there is apossibility of causing a state in which the optical paths are notarranged after cancellation of an already existing optical path.

If the management of the optical paths between the communication nodesis performed by doing the above, the optical paths between thecommunication nodes come to be always in an arranged state, and it ispossible to enhance the efficiency of use of the optical cross connectdevices.

It should be understood that the management method for the optical pathsbetween the communication nodes need not absolutely necessarily beaccording to this embodiment; it will be sufficient for it to be able toimplement the same functions, and such a type of method is also includedwithin the scope of the present invention.

The Sixth Embodiment

FIG. 23 is a figure showing the sixth embodiment according to thepresent invention, and this figure shows an example in which, in thefifth embodiment, along with utilizing the passive optical matrixswitch, the optical matrix switch control device is omitted.

In detail, in this figure, 6-1, 6-2, . . . 6-m are passive opticalmatrix switches, in which an optical signal which has been inputted froma certain input port is outputted from a different output port,according to the physical nature of this optical signal. As an example,the case may be considered in which an N input N outputarrayed-waveguide gratings are utilized for these optical matrixswitches. At this time, if a wavelength division demultiplexing circuit1 and a wavelength division multiplexing circuit 2 are supposed tohandle signals over a sufficiently wide wavelength band Δλ as signals ofthe same wavelength, the wavelengths of the optical signals which areinputted to the arrayed-waveguide grating may be supposed to bedifferent within the range of Δλ, and, due to the input-outputcharacteristic of an arrayed-waveguide grating, an optical signal whichhas been inputted from a certain input port is outputted from adifferent output port according to the physical nature of the opticalsignal which is inputted, i.e. according to its wavelength. Accordingly,in this embodiment, an optical path management device, for example 13 a,as a command for establishing or for canceling an optical path, onlyperforms command to the control devices for transceiver 11-1 through11-N of a wavelength of the optical signal to start or to stoptransmission and reception by the transceivers of the communicationnodes. It should be understood that the other structures and operationsof this embodiment are the same as in the case of the fifth embodiment.

The Seventh Embodiment

FIG. 24 is a figure showing the seventh embodiment according to thepresent invention; and, in this figure, there is shown an example inwhich, in the sixth embodiment, the function of an optical pathmanagement device is implemented by one among the N control devices fortransceiver.

That is to say, in this figure, 11-1 a is a control device fortransceiver which implements the function of the optical path managementdevice 13 a which was explained with regard to the sixth embodiment, andthis is connected via communication circuits 14 with the other controldevices for transceiver 11-2 through 11-N and sends and receivesinformation thereby, and performs management of the optical path in thesame manner as in the case of the sixth embodiment. It should beunderstood that the other structure and operations of this embodimentare the same as in the case of the fifth and the sixth embodiments.

It should be understood that it would also be acceptable to record aprogram for implementing the wavelength control and management ofoptical paths which has been explained above for the fourth through theseventh embodiments upon a recording medium which is capable of beingread by a computer, and to arrange for the program which is written uponthis recording medium to be read and executed by a computer system.

Here, the computer system includes an operating system and hardware suchas peripheral devices and the like. Furthermore, if the WWW system istaken advantage of, the computer system also includes a home pagepresentation environment (or a home page display environment).

Yet further, a recording medium which can be read by a computer includesa transportable medium such as a flexible disk, an opto-magnetic disk, aROM, a CD-ROM or the like, or a storage device which is housed within acomputer system such as a hard disk or the like. Even further, therecording medium which can be read by a computer includes a medium uponwhich the program is stored for a certain time period, such as avolatile memory (RAM) internal to a computer system which constitutes aserver or a client, when the program has been transmitted via a networksuch as the internet or the like, or via a communication circuit such asa telephone circuit or the like.

Moreover, the above-described program may acceptably be transmitted froma computer system in which this program is stored upon a storage deviceor the like to another computer system via a transmission medium or viaa transmission wave through a transmission medium. Here, a transmissionmedium which transmits the program includes a medium which is providedwith the function of transmitting information, such as a network (acommunication network) such as the internet or the like, or acommunication circuit (a communication line) such as a telephone circuitor the like. Yet further, the above-described program may acceptably beone for implementing a portion of the above-described functions. Evenfurther, it would be acceptable for it to be a so-called differentialfile (differential program) which is able to implement theabove-described functions in combination with a program which is alreadyrecorded upon the computer system.

INDUSTRIAL APPLICABILITY

According to the present invention, in an optical communication networksystem which takes advantage of a plurality of communication nodes andwavelength-routing to establish communication between thesecommunication nodes by route control according to the wavelength of anoptical signal, an arrayed-waveguide grating is provided independentlyfor each wavelength band in a wavelength-routing device, andwavelength-band multiplexing of the wavelength bands and wavelength-banddemultiplexing of the wavelength bands are performed in thecommunication nodes and in the wavelength-routing device. Accordingly,it is possible to form one optical path between the communication nodesfor each wavelength band. As a result, although with the conventionaltechnique in which only one optical path is established betweencommunication nodes there is a difficulty in establishing a plurality ofoptical paths between the communication nodes, by applying the structureof the present invention, it is possible to form, at a maximum, the samenumber of optical paths between the communication nodes as the number ofwavelength bands, so that it is possible to easily increase thetransmission capacity between the communication nodes. Furthermore, withthe optical communication network system of the present invention, whenincreasing the number of optical paths, it will be sufficient to add therequired equipment only between the communication nodes for which thisincrease of the number of optical paths is required, so that theextremely excellent and beneficial effect is obtained that theflexibility and the economy are both superb. Yet further, with aconventional optical communication system in which the optical paths areformed between the communication nodes for each wavelength-band, whenthe number of communication nodes exceeds the number of thewavelength-bands, it is necessary to pass via a different communicationnode. In contrast, according to the present invention, it is possible toimplement an optical communication network system which provides fullmesh connectivity in which optical paths between all the communicationnodes are provided. Accordingly, even if the number of communicationnodes exceeds the number of the wavelength-bands, it is not necessary topass via a different communication node. Furthermore, according to thepresent invention, in an optical cross connect device which is formed bya combination of a plurality of small scale optical matrix switches, theoptical paths between the communication nodes are always arranged, sothat it is possible to enhance the efficiency of utilization of theoptical cross connect device.

1. An optical communication network system comprising: a plurality ofcommunication nodes; a wavelength-routing device which establishescommunication between the communication nodes based upon route controlaccording to the wavelength of an optical signal; and an opticaltransmission line which forms a communication path which connects thecommunication nodes and the wavelength-routing device, wherein thewavelength-routing device comprises: N device input ports, where N beingan integer greater than or equal to 2, which are connected via theoptical transmission line to the communication nodes; N device outputports which are connected via the optical transmission line to thecommunication nodes; a plurality of wavelength-band demultiplexers whichare provided to each of the N device input ports, and each has a singleinput port and a plurality of output ports, and the input port isconnected to one of the device input ports; a plurality ofwavelength-band multiplexers which are provided to each of the N deviceoutput ports, and each has a plurality of input ports and a singleoutput port, and the output port is connected to one of the deviceoutput ports; and R K×K arrayed-waveguide gratings, where R being aninteger greater than or equal to J and J being an integer greater thanor equal to 2, which have K input ports and K output ports, where Kbeing an integer that satisfies K=N, which have wavelength-routingcharacteristics in which optical signals having different wavelengthswhich are inputted to one input port are output at different outputports depending on the wavelengths of the inputted optical signals andin which optical signals having different wavelengths which areoutputted from one output port are optical signals which have beeninputted to different input ports, and wherein the wavelength-banddemultiplexers comprise a means which demultiplexes by wavelength band awavelength division multiplexed signal in which a respectivepredetermined number of wavelengths have been wavelength divisionmultiplexed for each wavelength band which is transmitted from thecommunication nodes, where wavelength band=central wavelengthλB_(m)±wavelength band width Δλ_(m), withλB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), where 1=m=R−1, with m being an integer,and outputs the results at different output ports, the wavelength-bandmultiplexers comprise a means which multiplexes optical signals whichhave been inputted from the plurality of input ports for each wavelengthband and which outputs a wavelength division multiplexed signal in whicha predetermined number of wavelengths have been wavelength divisionmultiplexed at the output port, K×K arrayed-waveguide gratings areprovided with a wavelength-routing characteristic for each wavelengthband of central wavelength λB₁±wavelength band width Δλ₁, centralwavelength λB₂±wavelength band width Δλ₂ (λB₁+Δλ₁<λB₂−Δλ₂), centralwavelength λB₃±wavelength band width Δλ₃ (λB₂+Δλ₂<λB₃−Δλ₃), . . . ,central wavelength λB_(R)±wavelength band width Δλ_(R)(λB_(R−1)+Δλ_(R−1)<λB_(R)−Δλ_(R)), the output ports of thewavelength-band demultiplexers which are respectively connected to the Ndevice input ports are one to one connected to the input ports of theK×K arrayed-waveguide gratings which have wavelength-routingcharacteristics at the wavelength bands of the optical signals which areoutputted from the output ports of the wavelength-band demultiplexers,and the output ports of the K×K arrayed-waveguide gratings are one toone connected to the input ports of any one of the plurality ofwavelength-band multiplexers which can multiplex optical signals ofwavelengths which belong to the wavelength bands of the optical signalswhich are outputted from the output ports of the K×K arrayed-waveguidegratings.
 2. An optical communication network system as described inclaim 1, wherein each of the communication nodes comprises: a J×1wavelength-band multiplexer, where J being an integer greater than orequal to 2, which has J input ports IP [1], IP [2], IP [3], . . . IP [J]and a single output port, and output at the single output port opticalsignals of wavelengths which belong to the wavelength bands of centralwavelength λB₁±wavelength band width Δλ₁, central wavelengthλB₂±wavelength band width αλ₂, central wavelength λB₃±wavelength bandwidth Δλ₃, . . . , central wavelength λB_(J)±wavelength band widthΔλ_(J), which are inputted to the respective J input ports, whereλB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), for 1=m=j−1, where m being an integer;a plurality of wavelength division multiplexers which are provided ateach of the input ports IP [1], IP [2], IP [3], . . . IP [J] of the J×1wavelength-band multiplexer, and which have two or more input ports andone output port, with the output ports being connected to the inputports of the J×1 wavelength-band multiplexer; and a plurality of opticaltransmitters which are connected to the input ports of the wavelengthdivision multiplexers, and which emit light of wavelengths which belongto wavelength bands of central wavelengths, λB_(m)±wavelength band widthΔλm, and wherein the output port of the J×1 wavelength-band multiplexeris connected via an optical waveguide to the device input ports of thewavelength-routing device.
 3. An optical communication network system asdescribed in claim 1 or claim 2, wherein each of the communication nodescomprises: a 1×J wavelength-band demultiplexer, where J being an integergreater than or equal to 2, which has J output ports OP[1], OP[2],OP[3], . . . OP[J] and a single input port, and which outputs at the Joutput ports optical signals of wavelengths which belong to thewavelength band widths which are inputted to the single input port ofcentral wavelength λB₁±wavelength band width Δλ₁, central wavelengthλB₂±wavelength band width Δλ₂, central wavelength λB₃±wavelength bandwidth Δλ₃, . . . , central wavelength λB_(J)±wavelength band widthΔλ_(J), where λB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), where m being an integer;a plurality of wavelength division demultiplexers which are provided toeach of the output ports OP[1], OP[2], OP[3], . . . OP[J] of the 1×Jwavelength-band demultiplexer, each of which has two or more outputports and a single input port, and the input port is connected to one ofthe output ports of the 1×J wavelength-band demultiplexer; and aplurality of optical receivers which are connected to the output portsof the wavelength division demultiplexers, and wherein the single inputport of the 1×J wavelength-band demultiplexer is connected via anoptical waveguide to one of the device output ports of thewavelength-routing device.
 4. An optical communication network system asdescribed in claim 1, wherein each of the communication nodes comprises:a J×1 wavelength-band multiplexer, where J being an integer greater thanor equal to 2, which has J input ports IP [1], IP [2], IP [3], . . . IP[J] and a single output port, and outputs at the single output portoptical signals of wavelengths which belong to the wavelength bands ofcentral wavelength λB₁±wavelength band width Δλ₁, central wavelengthλB₂±wavelength band width Δλ₂, central wavelength λB₃±wavelength bandwidth Δλ₃, . . . , central wavelength λB_(J)±wavelength band widthΔλ_(J), which are inputted to each of the J input ports, whereλB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), for 1=m=J−1, where m being an integer;at least one wavelength-tunable optical light source integrated opticaltransmitter which is connected to any one of the input ports IP [1], IP[2], IP [3], . . . IP [J] of the J×1 wavelength-band multiplexer, whichis provided with a wavelength-tunable optical light source which can beset to a wavelength within a wavelength band which belongs to the inputport which is connected, and which outputs light of the wavelength; aplurality of wavelength division multiplexers which are provided to eachof the input ports of the J×1 wavelength-band multiplexer, other thanthe input port to which the wavelength-tunable optical light sourceintegrated optical transmitter is connected, and which have two or moreinput ports and one output port, with the output port being connected toone of the input ports of the J×1 wavelength-band multiplexer; aplurality of optical transmitters which are connected to the input portsof the wavelength division multiplexer, and which emit light ofwavelength which belongs to a wavelength band of central wavelengthλBm±wavelength band width Δλm; a 1×J wavelength-band demultiplexer,where J being an integer greater than or equal to 2, which has J outputports OP[1], OP[2], OP[3], . . . OP[J] and a single input port, and theoutputs at the J output ports optical signals of wavelengths whichbelong to the wavelength band widths of central wavelengthλB₁±wavelength band width Δλ₁, central wavelength λB₂±wavelength bandwidth Δλ₂, central wavelength λB₃±wavelength band width Δλ₃, . . . ,central wavelength λB_(J)±wavelength band width Δλ_(J), which areinputted to the single input port, whereλB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), for 1=m =J, where m being an integer;an optical receiver which is connected to that output port, among theoutput ports OP[1], OP[2], OP[3], . . . OP[J] of the 1×J wavelength-banddemultiplexer, which belongs to the wavelength band to which thewavelength-tunable optical light source integrated optical transmitteris provided, and which receives an optical signal of the wavelengthwhich is outputted from the wavelength-tunable optical light sourceintegrated optical transmitter; a plurality of wavelength divisiondemultiplexers which are provided to each of the output ports of the 1×Jwavelength-band demultiplexer, except for the output port to which theoptical receiver is connected, which have two or more output ports and asingle input port, and the input port is connected to one of the outputports of the 1×J wavelength-band demultiplexer; and a plurality ofoptical receivers which are connected to the output ports of thewavelength division demultiplexers, and wherein the single input port ofthe 1×J wavelength-band demultiplexer is connected via an opticalwaveguide to one of the device output ports of the wavelength-routingdevice.
 5. An optical communication network system as described in claim4, further comprising an optical path management means which controls anoptical path between two different communication nodes, and wherein ifat least one group of the wavelength-tunable optical light sourceintegrated optical transmitters exists which are provided to all thecommunication nodes and which output optical signals of the samewavelength band, and if there are K wavelength bands, where K being aninteger greater than or equal to 2, which belong to the input ports ofthe J×1 wavelength-band multiplexer which are connected to thewavelength-tunable optical light source integrated optical transmitters,the optical path management means assigns mutually different priorityrankings from 1 to K to the wavelength bands which belong to the inputports of the J×1 wavelength-band multiplexer which are connected to thewavelength-tunable optical light source integrated optical transmitters,and when, among the wavelength bands which belong to the input ports ofthe J×1 wavelength-band multiplexer which are connected to thewavelength-tunable optical light source integrated optical transmitters,the highest numbered priority ranking among the wavelength bands forwhich optical paths exist between x-th communication node and y-thcommunication node is number b, and the lowest numbered priority rankingamong the wavelength bands for which an optical path whose start pointis the x-th communication node, an optical path whose end point is thex-th communication node, an optical path whose start point is the y-thcommunication node, and an optical path whose end point is the y-thcommunication node do not exist is number a, and the number a is smallerthan the number b, the optical path management means establishes anoptical path between the x-th communication node and the y-thcommunication node upon the wavelength band of a-th priority ranking,and thereafter controls ON/OFF and an oscillation wavelength of thewavelength-tunable optical light source integrated optical transmitterso as to cancel the optical path which was established between the x-thcommunication node and the y-th communication node upon the wavelengthband of b-th priority ranking.
 6. An optical communication networksystem as described in claim 5, further comprising: a database whichrecords an optical path for each wavelength band; a first search meanswhich, when a requirement has arisen newly to establish an optical pathbetween xx-th communication node and yy-th communication node, searchesin the database, in order from data which correspond to a wavelengthband whose priority ranking is the lowest, for a wavelength band whichis not in use by the xx-th communication node and the yy-thcommunication node; a first transmission means which transmits to theoptical path management means a command for establishing an optical pathaccording to the result of searching by the first search means; a secondsearch means which, when a requirement for an optical path which isalready established between xxx-th communication node and yyy-thcommunication node has ceased, searches in the database, in order fromdata which correspond to a wavelength band whose priority ranking is thehighest, for a wavelength band upon which an optical path is establishedbetween the xxx-th communication node and the yyy-th communication node;a second transmission means which transmits to the optical pathmanagement means a command for canceling an optical path according tothe result of searching by the second search means; an extraction meanswhich searches in the database the number b of the highest priorityranking among the wavelength bands upon which optical paths areestablished between the x-th communication node and the y-thcommunication node, and the number a of the lowest priority rankingamong the wavelength bands upon which an optical path whose start pointis the x-th communication node, an optical path whose end point is thex-th communication node, an optical path whose start point is the y-thcommunication node, and an optical path whose end point is the y-thcommunication node do not exist, for all the combinations of x and y ina predetermined order, and extracts combinations of x, y, a, and b forwhich the number a is smaller than the number b; a third transmissionmeans which, when an applicable combination exists, transmits to theoptical path management means a command for establishing an optical pathusing the a-th wavelength band between the x-th communication node andthe y-th communication node, and thereafter transmits to the opticalpath management means a command for canceling an optical path using theb-th wavelength band between the x-th communication node and the y-thcommunication node; and a database update means which registers anoptical path which has been newly established in the database, anddeletes an optical path which has been cancelled from the database. 7.An optical communication network system as described in claim 1, whereinthe K×K arrayed-waveguide gratings have cyclic-wavelengthcharacteristics.
 8. A wavelength-routing device which is provided to anoptical communication network system comprising a plurality ofcommunication nodes and an optical transmission line which forms acommunication path, connected with the communication nodes by theoptical transmission line, and which establishes communication betweenthe communication nodes based upon route control according to thewavelength of an optical signal, the wavelength-routing devicecomprising: N device input ports, where N being an integer greater thanor equal to 2, which are connected via the optical transmission line tothe communication nodes; N device output ports which are connected viathe optical transmission line to the communication nodes; a plurality ofwavelength-band demultiplexers which are provided to each of the Ndevice input ports, and each has a single input port and a plurality ofoutput ports, and the input port is connected to one of the device inputports; a plurality of wavelength-band multiplexers which are provided toeach of the N device output ports, and each has a plurality of inputports and a single output port, and the output port is connected to oneof the device output ports; and R K×K arrayed-waveguide gratings, whereR being an integer greater than or equal to J and J being an integergreater than or equal to 2, which have K input ports and K output ports,where K being an integer that satisfies K=N, which havewavelength-routing characteristics in which optical signals havingdifferent wavelengths which are inputted to one input port are output atdifferent output ports depending on the wavelengths of the inputtedoptical signals and in which optical signals having differentwavelengths which are outputted from one output port are optical signalswhich have been inputted to different input ports, and wherein thewavelength-band demultiplexers comprise a means which demultiplexes bywavelength band a wavelength division multiplexed signal in which apredetermined number of wavelengths have been wavelength divisionmultiplexed for each wavelength band which is transmitted from thecommunication nodes, where wavelength band=central wavelengthλB_(m)±wavelength band width Δλ_(m) withλB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), where 1=m=R−1, with m being an integer,and outputs the results at different output ports, the wavelength-bandmultiplexers comprise a means which multiplexes optical signals whichhave been inputted from the plurality of input ports for each wavelengthband and which outputs a wavelength division multiplexed signal in whicha predetermined number of wavelengths have been wavelength divisionmultiplexed at the output port, the K×K arrayed-waveguide gratings areprovided with a wavelength-routing characteristic for each wavelengthband of central wavelength λB₁±wavelength band width Δλ₁, centralwavelength λB₂±wavelength band width Δλ₂ (λB₁+Δλ₁<λB₂−Δλ₂), centralwavelength λB₃±wavelength band width Δλ₃ (λB₂+Δλ₂<λB₃−Δλ₃), . . . ,central wavelength λB_(R)±wavelength band width Δλ_(R)(λB_(R−1)+Δλ_(R−1)<λB_(R)−Δλ_(R)), the output ports of thewavelength-band demultiplexers which are respectively connected to the Ndevice input ports are one to one connected to the input ports of theK×K arrayed-waveguide gratings which have wavelength-routingcharacteristics at the wavelength bands of the optical signals which areoutputted from the output ports of the wavelength-band demultiplexers,and the output ports of the K×K arrayed-waveguide gratings are one toone connected to the input ports of any one of the plurality ofwavelength-band multiplexers which can multiplex optical signals ofwavelengths which belong to the wavelength bands of the optical signalswhich are outputted from the output ports of the K×K arrayed-waveguidegratings.
 9. An optical path management device which controls an opticalpath between two different communication nodes in an opticalcommunication network system which comprises a plurality ofcommunication nodes, a wavelength-routing device which establishescommunication between the communication nodes based upon route controlaccording to the wavelength of an optical signal, and an opticaltransmission line which forms a communication path which connects thecommunication nodes and the wavelength-routing device wherein thewavelength-routing device comprises: N device input ports, where N beingan integer greater than or equal to 2, which are connected via theoptical transmission line to the communication nodes; N device outputports which are connected via the optical transmission line to thecommunication nodes; a plurality of wavelength-band demultiplexers whichare provided to each of the N device input ports, and each has a singleinput port and a plurality of output ports, and the input port isconnected to one of the device input ports; a plurality ofwavelength-band multiplexers which are provided to each of the N deviceoutput ports, and each has a plurality of input ports and a singleoutput port, and the output port is connected to one of the deviceoutput ports; and R K×K arrayed-waveguide gratings, where R being aninteger greater than or equal to J and J being an integer greater thanor equal to 2, which have K input ports and K output ports, where Kbeing an integer that satisfies K=N, which have wavelength-routingcharacteristics in which optical signals having different wavelengthswhich are inputted to one input port are output at different outputports depending on the wavelengths of the inputted optical signals andin which optical signals having different wavelengths which areoutputted from one output port are optical signals which have beeninputted to different input ports, and wherein the wavelength-banddemultiplexers comprise a means which demultiplexes by wavelength band awavelength division multiplexed signal in which a predetermined numberof wavelengths have been wavelength division multiplexed for eachwavelength band which is transmitted from the communication nodes,wherein wavelength band=central wavelength λB_(m)±wavelength band widthΔλ_(m), with λB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), where 1=m=R−1, with mbeing an integer, and outputs the results at different output ports, thewavelength-band multiplexers comprise a means which multiplexes opticalsignals which have been inputted from the plurality of input ports foreach wavelength band and which outputs a wavelength division multiplexedsignal in which a predetermined number of wavelengths have beenwavelength division multiplexed at the output port, the K×Karrayed-waveguide gratings are provided with a wavelength-routingcharacteristic for each wavelength band of central wavelengthλB₁±wavelength band width Δλ₁, central wavelength λB₂±wavelength bandwidth Δλ₂ (λB₁+Δλ₁<λB₂−Δλ₂), central wavelength λB₃±wavelength bandwidth Δλ₃ (λB₂+Δλ₂<λB₃−αλ₃), . . . , central wavelengthλB_(R)±wavelength band width Δλ_(R) (λB_(R−1)+Δλ_(R−1)<λB_(R)−Δλ_(R),)the output ports of the wavelength-band demultiplexers which arerespectively connected to the N device input ports are one to oneconnected to the input ports of the K×K arrayed-waveguide gratings whichhave wavelength-routing characteristics at the wavelength bands of theoptical signals which are outputted from the output ports of thewavelength-band demultiplexers, and the output ports of the K×Karrayed-waveguide gratings are one to one connected to the input portsof any one of the plurality of wavelength-band multiplexers which canmultiplex optical signals of wavelengths which belong to the wavelengthbands of the optical signals which are outputted from the output portsof the K×K arrayed-waveguide gratings, and each of the communicationnodes comprises: a J×1 wavelength-band multiplexer, where J being aninteger greater than or equal to 2, which has J input ports IP [1], IP[2], IP [3], . . . IP [J] and a single output port, and outputs at thesingle output port optical signals of wavelengths which belong to thewavelength bands of central wavelength λB₁±wavelength band width Δλ₁,central wavelength λB₂±wavelength band width Δλ₂, central wavelengthλB₃±wavelength band width Δλ₃, . . . , central wavelengthλB_(J)±wavelength band width Δλ_(J), which are inputted to each of the Jinput ports, where λB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), for 1=m=J−1, where mbeing an integer; at least one wavelength-tunable optical light sourceintegrated optical transmitter which is connected to any one of theinput ports IP [1], IP [2], IP [3], . . . IP [J] of the J×1wavelength-band multiplexer, which is provided with a wavelength-tunableoptical light source which can be set to a wavelength within awavelength band which belongs to the input port which is connected, andwhich outputs light of the wavelength; a plurality of wavelengthdivision multiplexers which are provided to each of the input ports ofthe J×1 wavelength-band multiplexer, other than the input port to whichthe wavelength-tunable optical light source integrated opticaltransmitter is connected, and which have two or more input ports and oneoutput port, with the output port being connected to one of the inputports of the J×1 wavelength-band multiplexer; a plurality of opticaltransmitters which are connected to the input ports of the wavelengthdivision multiplexer, and which emit light of wavelength which belongsto a wavelength band of central wavelength λBm±wavelength band widthΔλm; a 1×J wavelength-band demultiplexer, where J being an integergreater than or equal to 2, which has J output ports OP[1], OP[2],OP[3], . . . OP[J] and a single input port, and outputs at the J outputports optical signals of wavelengths which belong to the wavelength bandwidths of central wavelength λB₁±wavelength band width Δλ₁, centralwavelength λB₂±wavelength band width Δλ₂, central wavelengthλB₃±wavelength band width Δλ₃, . . . , central wavelengthλB_(J)±wavelength band width αλ_(J), which are inputted to the singleinput port, where λB_(m)+Δλ_(m)=λ_(m+1)−Δλ_(m+1), for 1=m=J, where mbeing an integer; an optical receiver which is connected to that outputport, among the output ports OP[1], OP[2], OP[3], . . . OP[J] of the 1×Jwavelength-band demultiplexer, which belongs to the wavelength band towhich the wavelength-tunable optical light source integrated opticaltransmitter is provided, and which receives an optical signal of thewavelength which is outputted from the wavelength-tunable optical lightsource integrated optical transmitter; a plurality of wavelengthdivision demultiplexers which are provided to each of the output portsof the 1×J wavelength-band demultiplexer, except for the output port towhich the optical receiver is connected, which have two or more outputports and a single input port, and the input port is connected to one ofthe output ports of the 1×J wavelength-band demultiplexer; and aplurality of optical receivers which are connected to the output portsof the wavelength division demultiplexers; and wherein the single inputport of the 1×J wavelength-band demultiplexer is connected via anoptical waveguide to one of the device output ports of thewavelength-routing device, and wherein the optical path managementdevice comprises: a means which, if at least one group of thewavelength-tunable optical light source integrated optical transmittersexists which are provided to all the communication nodes and whichoutput optical signals of the same wavelength band, and if there are Kwavelength bands, where K being an integer greater than or equal to 2,which belong to the input ports of the J×1 wavelength-band multiplexerwhich are connected to the wavelength-tunable optical light sourceintegrated optical transmitters, assigns mutually different priorityrankings from 1 to K to the wavelength bands which belong to the inputports of the J×1 wavelength-band multiplexer which are connected to thewavelength-tunable optical light source integrated optical transmitters;a means which detects that, among the wavelength bands which belong tothe input ports of the J×1 wavelength-band multiplexer which areconnected to the wavelength-tunable optical light source integratedoptical transmitters, the highest numbered priority ranking among thewavelength bands of optical paths between x-th communication node andy-th communication node is number b, and the lowest numbered priorityranking among the wavelength bands which are not used for an opticalpath whose start point is the x-th communication node, an optical pathwhose end point is the x-th communication node, an optical path whosestart point is the y-th communication node, and an optical path whoseend point is the y-th communication node is number a, and the number ais smaller than the number b; and a means which, if it has been detectedthat the number a is smaller than the number b, establishes an opticalpath between the x-th communication node and the y-th communication nodeupon the wavelength band of a-th priority ranking, and thereaftercontrols ON/OFF and an oscillation wavelength of the wavelength-tunableoptical light source integrated optical transmitter so as to cancel theoptical path which was established between the x-th communication nodeand the y-th communication node upon the wavelength band of b-thpriority ranking.
 10. An optical path management method which controlsan optical path between two different communication nodes in an opticalcommunication network system which comprises a plurality ofcommunication nodes, a wavelength-routing device which establishescommunication between the communication nodes based upon route controlaccording to the wavelength of an optical signal, and an opticaltransmission line which forms a communication path which connects thecommunication nodes and the wavelength-routing device, wherein thewavelength-routing device comprises: N device input ports, where N beingan integer greater than or equal to 2, which are connected via theoptical transmission line to the communication nodes; N device outputports which are connected via the optical transmission line to thecommunication nodes; a plurality of wavelength-band demultiplexers whichare provided to each of the N device input ports, and each has a singleinput port and a plurality of output ports, and the input port isconnected to one of the device input ports; a plurality ofwavelength-band multiplexers which are provided to each of the N deviceoutput ports, and each has a plurality of input ports and a singleoutput port, and the output port is connected to one of the deviceoutput ports; and R K×K arrayed-waveguide gratings, where R being aninteger greater than or equal to J and J being an integer greater thanor equal to 2, which have K input ports and K output ports, where Kbeing an integer that satisfies K=N, which have wavelength-routingcharacteristics in which optical signals having different wavelengthswhich are inputted to one input port are output at different outputports depending on the wavelengths of the inputted optical signals andin which optical signals having different wavelengths which areoutputted from one output port are optical signals which have beeninputted to different input ports, wherein the wavelength-banddemultiplexers comprise a means which demultiplexes by wavelength band awavelength division multiplexed optical signal in which a predeterminednumber of wavelengths have been wavelength division multiplexed for eachwavelength band which is transmitted from the communication nodes, wherewavelength band=central wavelength λB_(m)±wavelength band width Δλ_(m),with λB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), where 1=m=R−1, with m being aninteger, and outputs the results at different output ports, thewavelength-band multiplexers comprise a means which multiplexes opticalsignals which have been inputted from the plurality of input ports foreach wavelength band and which outputs a wavelength division multiplexedsignal in which a predetermined number of wavelengths have beenwavelength division multiplexed at the output port, the K×Karrayed-waveguide gratings are provided with a wavelength-routingcharacteristic for each wavelength band of central wavelengthλB₁±wavelength band width Δλ₁, central wavelength λB₂±wavelength bandwidth Δλ₂ (λB₁+Δλ₁<λB₂−Δλ₂), central wavelength λB₃ ±wavelength bandwidth Δλ₃ (λB₂+Δλ₂<λB₃−Δλ₃), . . . , central wavelengthλB_(R)±wavelength band width Δλ_(R) (λB_(R−1)+Δλ_(R−1)<λB_(R)−Δλ_(R)),the output ports of the wavelength-band demultiplexers which arerespectively connected to the N device input ports are one to oneconnected to the input ports of the K×K arrayed-waveguide gratings whichhave wavelength-routing characteristics at the wavelength bands of theoptical signals which are outputted from the output ports of thewavelength-band demultiplexers, and the output ports of the K×Karrayed-waveguide gratings are one to one connected to the input portsof any one of the plurality of wavelength-band multiplexers which canmultiplex optical signals of wavelengths which belong to the wavelengthbands of the optical signals which are outputted from the output portsof the K×K arrayed-waveguide gratings, and each of the communicationnodes comprises: a J×1 wavelength-band multiplexer, where J being aninteger greater than or equal to 2, which has J input ports IP [1], IP[2], IP [3], . . . IP [J] and a single output port, and outputs at thesingle output port optical signals of wavelengths which belong to thewavelength bands of central wavelength λB₁±wavelength band width Δλ₁,central wavelength λB₂±wavelength band width Δλ₂, central wavelengthλB₃±wavelength band width Δλ₃, . . . , central wavelengthλB_(J)±wavelength band width Δλ_(J), which are inputted to each of the Jinput ports, where λB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), for 1=m=J−1, where mbeing an integer; at least one wavelength-tunable optical light sourceintegrated optical transmitter which is connected to any one of theinput ports IP [1], IP [2], IP [3], . . . IP [J] of the J×1wavelength-band multiplexer, which is provided with a wavelength-tunableoptical light source which can be set to a wavelength within awavelength band which belongs to the input port which is connected, andwhich outputs light of the wavelength; a plurality of wavelengthdivision multiplexers which are provided to each of the input ports ofthe J×1 wavelength-band multiplexer, other than the input port to whichthe wavelength-tunable optical light source integrated opticaltransmitter is connected, and which have two or more input ports and oneoutput port, with the output port being connected to one of the inputports of the J×1 wavelength-band multiplexer; a plurality of opticaltransmitters which are connected to the input ports of the wavelengthdivision multiplexer, and which emit light of wavelength which belongsto a wavelength band of central wavelength λB_(m)±wavelength band widthΔλm; a 1×J wavelength-band demultiplexer, where J being an integergreater than or equal to 2, which has J output ports OP[1], OP[2],OP[3], . . . OP[J] and a single input port, and outputs at the J outputports optical signals of wavelengths which belong to the wavelength bandwidths of central wavelength λB₁±wavelength band width Δλ₁, centralwavelength λB₂±wavelength band width Δλ₂, central wavelengthλB₃±wavelength band width Δλ₃, . . ., central wavelengthλB_(J)±wavelength band width Δλ_(J), which are inputted to the singleinput port, where λB_(m)+Δλ_(m)=λB_(m+1)−Δλ_(m+1), for 1=m=J, where mbeing an integer; an optical receiver which is connected to that outputport, among the output ports OP[1], OP[2], OP[3], . . . OP[J] of the 1×Jwavelength-band demultiplexer, which belongs to the wavelength band towhich the wavelength-tunable optical light source integrated opticaltransmitter is provided, and which receives an optical signal of thewavelength which is outputted from the wavelength-tunable optical lightsource integrated optical transmitter; a plurality of wavelengthdivision demultiplexers which are provided to each of the output portsof the 1×J wavelength-band demultiplexer, except for the output port towhich the optical receiver is connected, which have two or more outputports and a single input port, and the input port is connected to one ofthe output ports of the 1×J wavelength-band demultiplexer; and aplurality of optical receivers which are connected to the output portsof the wavelength division demultiplexers, and wherein the single inputport of the 1×J wavelength-band demultiplexer is connected via anoptical waveguide to one of the device output ports of thewavelength-routing device, and the optical path management methodcomprises: a step of, if at least one group of the wavelength-tunableoptical light source integrated optical transmitters exists which areprovided to all the communication nodes and which output optical signalsof the same wavelength band, and if there are K wavelength bands, whereK being an integer greater than or equal to 2, which belong to the inputports of the J×1 wavelength-band multiplexer which are connected to thewavelength-tunable optical light source integrated optical transmitters,assigning mutually different priority rankings from 1 to K to thewavelength bands which belong to the input ports of the J×1wavelength-band multiplexer which are connected to thewavelength-tunable optical light source integrated optical transmitters;a step of, when, among the wavelength bands which belong to the inputports of the J×1 wavelength-band multiplexer which are connected to thewavelength-tunable optical light source integrated optical transmitter,the highest numbered priority ranking among the wavelength bands forwhich an optical path exists between x-th communication node and y-thcommunication node is number b, and the lowest numbered priority rankingamong the wavelength bands for which an optical path whose start pointis the x-th communication node, an optical path whose end point is thex-th communication node, an optical path whose start point is the y-thcommunication node, and an optical path whose end point is the y-thcommunication node do not exist is number a, and the number a is smallerthan the number b; and controlling ON/OFF and an oscillation wavelengthof the wavelength-tunable optical light source integrated opticaltransmitter so as to establish an optical path between the x-thcommunication node and the y-th communication node upon the wavelengthband of a-th priority ranking; and a step of establishing an opticalpath between the x-th communication node and the y-th communication nodeupon the wavelength band of the a-th priority ranking, and thereaftercontrolling ON/OFF and the oscillation wavelength of thewavelength-tunable optical light source integrated optical transmitterso as to cancel the optical path which was established between the x-thcommunication node and the y-th communication node upon the wavelengthband of b-th priority ranking.
 11. An optical path management programwhich causes a computer to execute the steps of the optical pathmanagement method as described in claim
 10. 12. A recording medium whichcan be read by a computer, upon which the optical path managementprogram as described in claim 11 is recorded.